Merging Date and time

I have an eddy pro file that has date in datetime format and time in cell array. How do I merge them into single datetime? I have tried couple of codes with no luck. Thanks.

Answer 1

[Stephen23]

Rather than fiddling after importing, the best approach is to import the file correctly using READTABLE options, e.g.:

fnm = 'LI7500_eddypro_LP_2023_JFM_full_output_2023-04-17T105102_adv.csv';
opt = detectImportOptions(fnm, 'VariableNamesLine',2, 'VariableUnitsLine',3, 'VariableNamingRule','preserve');
opt = setvartype(opt, 'time','duration');
opt = setvartype(opt, 'date','datetime');
opt = setvaropts(opt, 'time','InputFormat','hh:mm');
opt = setvaropts(opt, 'date','InputFormat','M/d/yy');

Then the importing of every identically-formatted file is very simple, as well as adding the date+time:

tbl = readtable(fnm,opt)

tbl = 6×185 table
                 filename                  date     time      DOY     daytime    file_records    used_records      Tau       qc_Tau    rand_err_Tau       H       qc_H    rand_err_H       LE       qc_LE    rand_err_LE    co2_flux    qc_co2_flux    rand_err_co2_flux    h2o_flux    qc_h2o_flux    rand_err_h2o_flux    ch4_flux     qc_ch4_flux    rand_err_ch4_flux    none_flux    qc_none_flux    rand_err_none_flux    H_strg     LE_strg    co2_strg    h2o_strg    ch4_strg    none_strg    co2_v-adv    h2o_v-adv    ch4_v-adv    none_v-adv    co2_molar_density    co2_mole_fraction    co2_mixing_ratio    co2_time_lag    co2_def_timelag    h2o_molar_density    h2o_mole_fraction    h2o_mixing_ratio    h2o_time_lag    h2o_def_timelag    ch4_molar_density    ch4_mole_fraction    ch4_mixing_ratio    ch4_time_lag    ch4_def_timelag    none_molar_density    none_mole_fraction    none_mixing_ratio    none_time_lag    none_def_timelag    sonic_temperature    air_temperature    air_pressure    air_density    air_heat_capacity    air_molar_volume       ET        water_vapor_density      e         es      specific_humidity      RH       VPD       Tdew     u_unrot     v_unrot     w_unrot     u_rot       v_rot       w_rot     wind_speed    max_wind_speed    wind_dir     yaw      pitch    roll      u*         TKE         L        (z-d)/L    bowen_ratio      T*       model    x_peak    x_offset    x_10%     x_30%     x_50%     x_70%    x_90%      un_Tau     Tau_scf     un_H      H_scf      un_LE      LE_scf    un_co2_flux    co2_scf    un_h2o_flux    h2o_scf    un_ch4_flux    ch4_scf    un_none_flux    un_none_scf    spikes_hf    amplitude_resolution_hf    drop_out_hf    absolute_limits_hf    skewness_kurtosis_hf    skewness_kurtosis_sf    discontinuities_hf    discontinuities_sf    timelag_hf    timelag_sf    attack_angle_hf    non_steady_wind_hf    u_spikes    v_spikes    w_spikes    ts_spikes    co2_spikes    h2o_spikes    ch4_spikes    none_spikes    head_detect_LI-7200    t_out_LI-7200    t_in_LI-7200    aux_in_LI-7200    delta_p_LI-7200    chopper_LI-7200    detector_LI-7200    pll_LI-7200    sync_LI-7200    chopper_LI-7500    detector_LI-7500    pll_LI-7500    sync_LI-7500    not_ready_LI-7700    no_signal_LI-7700    re_unlocked_LI-7700    bad_temp_LI-7700    laser_temp_unregulated_LI-7700    block_temp_unregulated_LI-7700    motor_spinning_LI-7700    pump_on_LI-7700    top_heater_on_LI-7700    bottom_heater_on_LI-7700    calibrating_LI-7700    motor_failure_LI-7700    bad_aux_tc1_LI-7700    bad_aux_tc2_LI-7700    bad_aux_tc3_LI-7700    box_connected_LI-7700    mean_value_RSSI_LI-7200    mean_value_LI-7500     u_var      v_var      w_var     ts_var     co2_var     h2o_var    ch4_var     none_var    w/ts_cov    w/co2_cov    w/h2o_cov    w/ch4_cov    w/none_cov    air_t_mean    vin_sf_mean    co2_mean    h2o_mean    dew_point_mean    co2_signal_strength_7500_mean    ch4_mean    air_p_mean    rssi_77_mean
    __________________________________    ______    _____    _____    _______    ____________    ____________    ________    ______    ____________    _______    ____    __________    ________    _____    ___________    ________    ___________    _________________    ________    ___________    _________________    _________    ___________    _________________    _________    ____________    __________________    _______    _______    ________    ________    ________    _________    _________    _________    _________    __________    _________________    _________________    ________________    ____________    _______________    _________________    _________________    ________________    ____________    _______________    _________________    _________________    ________________    ____________    _______________    __________________    __________________    _________________    _____________    ________________    _________________    _______________    ____________    ___________    _________________    ________________    _________    ___________________    ______    ______    _________________    ______    ______    ______    ________    ________    _______    _______    _________    _______    __________    ______________    ________    ______    _____    ____    _______    _______    ________    _______    ___________    _______    _____    ______    ________    ______    ______    ______    _____    ______    ________    _______    _______    ______    ________    ______    ___________    _______    ___________    _______    ___________    _______    ____________    ___________    _________    _______________________    ___________    __________________    ____________________    ____________________    __________________    __________________    __________    __________    _______________    __________________    ________    ________    ________    _________    __________    __________    __________    ___________    ___________________    _____________    ____________    ______________    _______________    _______________    ________________    ___________    ____________    _______________    ________________    ___________    ____________    _________________    _________________    ___________________    ________________    ______________________________    ______________________________    ______________________    _______________    _____________________    ________________________    ___________________    _____________________    ___________________    ___________________    ___________________    _____________________    _______________________    __________________    _______    _______    _______    _______    ________    _______    ________    ________    ________    _________    _________    _________    __________    __________    ___________    ________    ________    ______________    _____________________________    ________    __________    ____________

    {'2023-01-09T160000_AIU-1485.ghg'}    1/9/23    16:30    9.687       1          17935           17935          0.0665      1           NaN         -14.738     1         NaN          26.778      1          NaN          0.0367         2                NaN           0.60063          1                NaN             0.00191         2                NaN              NaN           NaN                NaN                NaN        NaN         NaN         NaN         NaN       NaN        -401.12      -7.4227      -2.1283        NaN              16.96                387.3               390.11              0.2               0                313.85               7.1671               7.2188                0               0                  0.09               2.0783               2.0934              2.1               0                  NaN                   NaN                   NaN                NaN                9                 284.22              284.13          1.0345e+05        1.265            1009.2               0.0228            0.0389          0.00566           741.6      1307         0.00447         56.742    565.37    275.85      0.0297     -1.7682    0.21998     1.7818     6.68e-16    -0.0237      1.7819          3.8905         69.039     271.12     NaN     NaN     0.22929    0.30973      73.058    0.37449     -0.55036      -0.0503      0      186.89    -28.361     64.154    159.75    243.63    341.7    511.92      0.0659    1.0093     -13.106    1.0065      26.491    1.0251      0.48109      1.0251       0.59418      1.0251        0.00422     1.1024         NaN             NaN          8e+08               8e+08                8e+08             8e+08                     8e+08                   8e+08               8e+08                 8e+08             81110         81110             80                   80                4          10          1           27             6             7            0             NaN                NaN                 NaN             NaN              NaN                NaN                NaN                NaN               NaN            NaN                0                  0                 0              0                  0                    0                     0                    0                          0                                 0                             0                      0                     0                         0                         0                       0                     16028                  16028                  16028                   16028                      NaN                     100            0.21354    0.19176    0.21417     0.0283     0.00137    26.625     2.35e-07      NaN        -0.0103     0.000481     0.59418      4.22e-06       NaN          285.13           0          388.63      7.2342         2.7633                   103.81                 2.0718     1.0152e+05       42.415   
    {'2023-01-09T163000_AIU-1485.ghg'}    1/9/23    17:00    9.708       0          17903           17903          0.0166      1           NaN         -12.721     1         NaN          7.0114      1          NaN         -0.0921         1                NaN           0.15717          1                NaN             -0.0102         1                NaN              NaN           NaN                NaN            -12.121     1.1637     0.99663      0.0261      0.0161       NaN        -242.37      -4.4919      -1.2962        NaN             17.059               388.73               391.61              0.1               0                316.17               7.2045               7.2568              0.1               0                0.0912               2.1015               2.1171             -1.7               0                  NaN                   NaN                   NaN                NaN                9                 283.64              283.54          1.0345e+05       1.2676            1009.2               0.0228            0.0102           0.0057           745.5    1256.2         0.00449         59.343    510.75    275.92    -0.15911     -1.2705    0.15138     1.2886     4.24e-16    -0.0142      1.2887          3.3667         77.138     263.12     NaN     NaN      0.1146     0.1211      10.566     2.5894      -1.8143      -0.0868      1      235.34        103        217       444       831     1794      7645      0.0165    1.0076       -12.2     1.011      6.9526    1.0723      0.41505      1.0723       0.15586      1.0723       -0.00491     1.3468         NaN             NaN          8e+08               8e+08                8e+08             8e+08                     8e+08               8.011e+08               8e+08                 8e+08             80100         80100             80                   81               18          15          2           13            18             9            0             NaN                NaN                 NaN             NaN              NaN                NaN                NaN                NaN               NaN            NaN                0                  0                 0              0                  0                    0                     0                    0                          0                                 0                             0                      0                     0                         0                         0                       0                     17778                  17778                  17778                   17778                      NaN                     100            0.13076     0.0369     0.0746     0.0403    0.000594    20.289     9.46e-08      NaN       -0.00954     0.000415     0.15586     -4.91e-06       NaN          283.86           0          389.15      7.3729         3.0325                    103.8                 2.0948     1.0152e+05       42.366   
    {'2023-01-09T170000_AIU-1485.ghg'}    1/9/23    17:30    9.729       0          18000           18000          0.0042      1           NaN          5.7231     2         NaN         -2.8692      1          NaN         -0.2457         1                NaN           -0.0642          1                NaN            -0.00367         1                NaN              NaN           NaN                NaN            -42.241    -9.2783    -0.34004    -0.20758      0.0021       NaN         -853.1      -15.181      -4.5823        NaN             17.166               388.25               391.21             -0.6               0                305.47               6.9089                6.957             -0.6               0                0.0922               2.1045               2.1206             -2.1               0                  NaN                   NaN                   NaN                NaN                9                 282.86              281.48          1.0347e+05       1.2773              1009               0.0226          -0.00416           0.0055          715.05    1093.9         0.00431         65.368    378.83    275.33     0.19319    -0.88732    0.12718    0.91694     2.29e-16    -0.0497     0.91828          1.4566         57.717     282.37     NaN     NaN      0.0573     0.0288     -2.9419    -9.3002      -1.9946       0.0774      1       100.4         45         78       125       184      285       602     0.00391    1.0741      5.2987    1.0487     -2.9055    1.0548     -0.46602      1.0548        -0.065      1.0548       -0.00481     1.0889         NaN             NaN          8e+08               8e+08                8e+08             8e+08                     8e+08               8.001e+08               8e+08                 8e+08             80000         80000             80                   81               18           6          1            4             0            12            0             NaN                NaN                 NaN             NaN              NaN                NaN                NaN                NaN               NaN            NaN                0                  0                 0              0                  0                    0                     0                    0                          0                                 0                             0                      0                     0                         0                         0                       0                     18000                  18000                  18000                   18000                      NaN                     100             0.0136     0.0379    0.00614    0.11397    0.000952    17.661     8.23e-08      NaN        0.00411    -0.000466      -0.065     -4.81e-06       NaN          281.95           0          388.86      7.5936         3.4526                   103.78                 2.0979     1.0155e+05       42.044   
    {'2023-01-09T173000_AIU-1485.ghg'}    1/9/23    18:00    9.749       0          18000           18000        0.000491      1           NaN          0.0756     2         NaN          2.2866      1          NaN         -0.0281         2                NaN            0.0511          1                NaN            2.23e-06         1                NaN              NaN           NaN                NaN            -36.517    -5.8353     0.76599    -0.13033     0.00283       NaN        -989.78      -17.096       -5.318        NaN             17.329               389.33               392.35             -0.6               0                299.31               6.7245               6.7701              0.6               0                0.0931               2.1086               2.1249             -1.3               0                  NaN                   NaN                   NaN                NaN                9                 281.07              279.71          1.0351e+05       1.2859            1008.9               0.0225           0.00331          0.00539          696.25    969.52         0.00419         71.814    273.27    274.96     0.21159    -0.26596     0.0588    0.34491    -6.19e-17    -0.0571     0.34961         0.94274         31.496     308.33     NaN     NaN      0.0195     0.0209     -8.8214    -3.1015       0.0331      0.00298      1      185.49         83        144       233       343      534      1140    0.000429    1.1451     0.18896    1.0968      2.0548    1.1039      -0.0467      1.1039        0.0459      1.1039      -0.000155     1.1456         NaN             NaN          8e+08               8e+08                8e+08             8e+08                     8e+08                   8e+08               8e+08                 8e+08             80000         80000             80                   81                1           0          0            2             0             1            0             NaN                NaN                 NaN             NaN              NaN                NaN                NaN                NaN               NaN            NaN                0                  0                 0              0                  0                    0                     0                    0                          0                                 0                             0                      0                     0                         0                         0                       0                     18000                  18000                  18000                   18000                      NaN                     100             0.0297     0.0105    0.00147    0.79534     0.00722    33.623     9.67e-08      NaN       0.000146    -4.67e-05      0.0459     -1.55e-07       NaN          280.09           0          389.81      7.7078         3.6694                   103.75                 2.1019     1.0158e+05       41.785   
    {'2023-01-09T180000_AIU-1485.ghg'}    1/9/23    18:30     9.77       0          18000           18000        0.000438      1           NaN         -1.2536     0         NaN        -0.49682      0          NaN          0.0592         1                NaN           -0.0111          0                NaN            -0.00531         0                NaN              NaN           NaN                NaN            -38.084     1.1723      2.2123      0.0261     -0.0036       NaN        -1258.7      -21.685       -6.701        NaN             17.587               392.44               395.53              0.6               0                   303               6.7613               6.8073             -0.6               0                0.0936               2.1035                 2.12             -2.1               0                  NaN                   NaN                   NaN                NaN                9                 279.64              277.89          1.0354e+05       1.2947            1008.9               0.0223         -0.000718          0.00546          700.22    854.02         0.00422         81.991     153.8    275.04     0.10415    -0.00275    0.00168    0.10332    -7.04e-17    -0.0716     0.12569         0.38919         341.51     358.39     NaN     NaN      0.0184    0.00926     0.44324     61.727       2.5232      -0.0522      1      5.6053          2          5         9        16       32       109    0.000412    1.0627     -1.1358    1.1212    -0.26417    1.6903       0.0736      1.6903      -0.00589      1.6903      -0.000928     5.2186         NaN             NaN          8e+08               8e+08                8e+08             8e+08                     8e+08                   8e+08               8e+08                 8e+08             81000         81000             81                   81                2           9          0            0             0             0            0             NaN                NaN                 NaN             NaN              NaN                NaN                NaN                NaN               NaN            NaN                0                  0                 0              0                  0                    0                     0                    0                          0                                 0                             0                      0                     0                         0                         0                       0                     18000                  18000                  18000                   18000                      NaN                     100             0.0118      0.005    0.00168    0.14606     0.00763    17.434     6.13e-08      NaN       -0.00087     7.36e-05    -0.00589     -9.28e-07       NaN           278.3           0          392.99      7.8211         3.8806                   103.71                 2.0966      1.016e+05       40.409   
    {'2023-01-09T183000_AIU-1485.ghg'}    1/9/23    19:00    9.791       0          18000           18000        0.000412      1           NaN          1.9632     2         NaN          1.2987      1          NaN        -0.88109         1                NaN            0.0289          1                NaN           -0.000768         1                NaN              NaN           NaN                NaN            -25.038    -1.1225      3.5124      -0.025    -0.00132       NaN        -1097.2      -18.573      -5.7674        NaN              17.89               397.35               400.48             -0.6               0                302.84               6.7263               6.7719              0.6               0                 0.094               2.1016               2.1182              2.1               0                  NaN                   NaN                   NaN                NaN                9                 278.41              276.69          1.0357e+05       1.3008            1008.9               0.0222           0.00187          0.00546          696.85    785.19          0.0042         88.749    88.339    274.97     0.10182    -0.10158     0.0218    0.14544    -1.42e-16    -0.0613     0.15784          0.5507         24.933     314.76     NaN     NaN      0.0178      0.009    -0.25643     -106.7       1.5117       0.0841      1      16.632          8         13        21        30       47        99    0.000336    1.2271      1.7659    1.1535      1.0462    1.1626     -0.85092      1.1626        0.0233      1.1626       -0.00121      1.217         NaN             NaN          8e+08               8e+08                8e+08             8e+08                8.0001e+08              8.0011e+08               8e+08                 8e+08             80110         80110             81                   81                7          24          0            4             1             4            0             NaN                NaN                 NaN             NaN              NaN                NaN                NaN                NaN               NaN            NaN                0                  0                 0              0                  0                    0                     0                    0                          0                                 0                             0                      0                     0                         0                         0                       0                     18000                  18000                  18000                   18000                      NaN                     100            0.00901    0.00707    0.00191    0.46931      0.0294    20.456     6.77e-08      NaN        0.00135    -0.000851      0.0233     -1.21e-06       NaN          277.08           0          397.87      7.8389         3.9175                   103.67                 2.0946     1.0162e+05       38.505   

dt = tbl.date + tbl.time;
dt.Format = 'uuuu-MM-dd HH:mm:ss'

dt = 6×1 datetime array
   2023-01-09 16:30:00
   2023-01-09 17:00:00
   2023-01-09 17:30:00
   2023-01-09 18:00:00
   2023-01-09 18:30:00
   2023-01-09 19:00:00

[Askic V]

Great demonstration @Stephen23. Thank you!

[Benju Baniya]

Hello, Thank you so much for your answer. For some reason, my date is converted to NaT and final datetime is nat as well. I am using the same script. I tried chaging input format to yyyy/MM/dd as well. And this was the code I was using-- tried changing inputformat for date and time in different ways

fnm = 'LI7500_eddypro_LP_2023_JFM_full_output_2023-04-17T105102_adv.csv';

opt = detectImportOptions(fnm, 'VariableNamesLine',2, 'VariableUnitsLine',3, 'VariableNamingRule','preserve');

opt = setvartype(opt, 'time','duration');

opt = setvartype(opt, 'date','datetime'); %changes it to nat

opt = setvaropts(opt, 'time','InputFormat','hh:mm');

opt = setvaropts(opt, 'date','InputFormat', 'yyyy/MM/dd');

tbl = readtable(fnm,opt);

dt = tbl.date + tbl.time;

dt.Format = 'uuuu-MM-dd HH:mm:ss'

Also why did you use this input format -.opt = setvaropts(opt, 'date','InputFormat','M/d/yy'); when originally it was in the format yyyy/MM/dd.

[Stephen23]

"For some reason, my date is converted to NaT and final datetime is nat as well."

Because you used a date format that does not match the dates in your textfile.

"I am using the same script."

No, you are not: you changed the date format to something that does not match your textfile's dates.

"I tried chaging input format to yyyy/MM/dd as well."

Why?

"Also why did you use this input format -.opt = setvaropts(opt, 'date','InputFormat','M/d/yy');"

Because that is the format of the dates in your textfile.

Note that using the correct format also gives the correct year (unlike the answer that you accepted).

"when originally it was in the format yyyy/MM/dd."

Nope, that is incorrect. The dates in your textfile are actually formatted as M/d/yy. Here they are:

Do those dates look anything like "yyyy/MM/dd" as you claim? Totally different order, varying widths... nope.

Perhaps you made the (very common) mistake of opening a CSV file in MS Excel, and imagined that MS Excel shows or saves the data in the file exactly as it occurs in the textfile. It doesn't. If you want to see what is in a textfile (like a CSV file) then you need to use a text editor, not MS Excel.

Data-Mangling is a very well-known problem with MS Excel, and occurs in many different ways, e.g.:

https://www.theverge.com/2020/8/6/21355674/human-genes-rename-microsoft-excel-misreading-dates

Note that by default READTABLE also does not return those dates in exactly the same format they occur in the textfile either. Certainly very close, but not exactly the same. Lets try it right now:

fnm = 'LI7500_eddypro_LP_2023_JFM_full_output_2023-04-17T105102_adv.csv';
readtable(fnm)

Warning: The DATETIME data was created using format 'MM/dd/uuuu' but also matched 'dd/MM/uuuu'.
To avoid ambiguity, supply a datetime format using SETVAROPTS, e.g.
opts = setvaropts(opts,varname,'InputFormat','MM/dd/uuuu');

Warning: Column headers from the file were modified to make them valid MATLAB identifiers before creating variable names for the table. The original column headers are saved in the VariableDescriptions property.
Set 'VariableNamingRule' to 'preserve' to use the original column headers as table variable names.

ans = 6×185 table
                file_info                    Var2         Var3       Var4     Var5    Var6     Var7     corrected_fluxes_and_quality_flags    Var9    Var10     Var11     Var12    Var13     Var14      Var15    Var16     Var17      Var18    Var19     Var20     Var21    Var22      Var23      Var24    Var25    Var26    Var27    Var28    storage_fluxes     Var30      Var31       Var32       Var33      Var34    vertical_advection_fluxes     Var36      Var37     Var38    gas_densities_concentrations_and_timelags    Var40     Var41     Var42    Var43    Var44     Var45     Var46     Var47    Var48    Var49     Var50     Var51     Var52    Var53    Var54    Var55    Var56    Var57    Var58    air_properties    Var60       Var61       Var62     Var63     Var64       Var65       Var66     Var67     Var68      Var69     Var70     Var71     Var72     unrotated_wind     Var74       Var75     rotated_wind      Var77       Var78      Var79      Var80     Var81     rotation_angles_for_tilt_correction    Var83    Var84    turbulence     Var86      Var87       Var88      Var89       Var90     footprint    Var92      Var93     Var94     Var95     Var96     Var97    Var98     uncorrected_fluxes_and_spectral_correction_factors__scf_    Var100    Var101     Var102     Var103     Var104     Var105     Var106     Var107     Var108     Var109      Var110    Var111    Var112    statistical_flags    Var114    Var115    Var116      Var117        Var118      Var119    Var120    Var121    Var122    Var123    Var124    spikes    Var126    Var127    Var128    Var129    Var130    Var131    Var132    diagnostic_flags_LI_7200    Var134    Var135    Var136    Var137    Var138    Var139    Var140    Var141    diagnostic_flags_LI_7500    Var143    Var144    Var145    diagnostic_flags_LI_7700    Var147    Var148    Var149    Var150    Var151    Var152    Var153    Var154    Var155    Var156    Var157    Var158    Var159    Var160    Var161    RSSI_LI_7200    RSSI_LI_7500    variances    Var165     Var166     Var167      Var168     Var169     Var170     Var171    covariances     Var173       Var174      Var175      Var176    custom_variables    Var178    Var179    Var180    Var181    Var182    Var183      Var184      Var185
    __________________________________    __________    _________    _____    ____    _____    _____    __________________________________    ____    _____    _______    _____    _____    ________    _____    _____    ________    _____    _____    _______    _____    _____    _________    _____    _____    _____    _____    _____    ______________    _______    ________    ________    ________    _____    _________________________    _______    _______    _____    _________________________________________    ______    ______    _____    _____    ______    ______    ______    _____    _____    ______    ______    ______    _____    _____    _____    _____    _____    _____    _____    ______________    ______    __________    ______    ______    ______    _________    _______    ______    ______    _______    ______    ______    ______    ______________    ________    _______    ____________    _________    _______    _______    _______    ______    ___________________________________    _____    _____    __________    _______    ________    _______    ________    _______    _________    ______    _______    ______    ______    ______    _____    ______    ________________________________________________________    ______    _______    ______    ________    ______    ________    ______    ________    ______    _________    ______    ______    ______    _________________    ______    ______    ______    __________    __________    ______    ______    ______    ______    ______    ______    ______    ______    ______    ______    ______    ______    ______    ______    ________________________    ______    ______    ______    ______    ______    ______    ______    ______    ________________________    ______    ______    ______    ________________________    ______    ______    ______    ______    ______    ______    ______    ______    ______    ______    ______    ______    ______    ______    ______    ____________    ____________    _________    _______    _______    _______    ________    ______    ________    ______    ___________    _________    ________    _________    ______    ________________    ______    ______    ______    ______    ______    ______    __________    ______

    {'2023-01-09T160000_AIU-1485.ghg'}    01/09/0023    {'16:30'}    9.687     1      17935    17935                   0.0665                  1       NaN     -14.738      1       NaN       26.778      1       NaN       0.0367      2       NaN     0.60063      1       NaN       0.00191      2       NaN      NaN      NaN      NaN            NaN            NaN         NaN         NaN         NaN     NaN              -401.12             -7.4227    -2.1283     NaN                       16.96                       387.3    390.11     0.2       0      313.85    7.1671    7.2188       0       0        0.09    2.0783    2.0934     2.1       0       NaN      NaN      NaN      NaN       9          284.22        284.13    1.0345e+05     1.265    1009.2    0.0228       0.0389    0.00566     741.6      1307    0.00447    56.742    565.37    275.85         0.0297        -1.7682    0.21998       1.7818        6.68e-16    -0.0237     1.7819     3.8905    69.039                  271.12                    NaN      NaN      0.22929      0.30973      73.058    0.37449    -0.55036    -0.0503        0        186.89    -28.361    64.154    159.75    243.63    341.7    511.92                              0.0659                            1.0093    -13.106    1.0065      26.491    1.0251     0.48109    1.0251     0.59418    1.0251      0.00422    1.1024     NaN       NaN            8e+08          8e+08     8e+08     8e+08          8e+08         8e+08    8e+08     8e+08     81110     81110       80        80         4        10        1         27         6         7        0        NaN                NaN                NaN       NaN       NaN       NaN       NaN       NaN       NaN       NaN                 0                  0         0         0                  0                  0         0         0         0         0         0         0         0         0         0         0       16028     16028     16028     16028         NaN             100          0.21354     0.19176    0.21417     0.0283     0.00137    26.625    2.35e-07     NaN        -0.0103       0.000481     0.59418     4.22e-06     NaN           285.13           0       388.63    7.2342    2.7633    103.81    2.0718    1.0152e+05    42.415
    {'2023-01-09T163000_AIU-1485.ghg'}    01/09/0023    {'17:00'}    9.708     0      17903    17903                   0.0166                  1       NaN     -12.721      1       NaN       7.0114      1       NaN      -0.0921      1       NaN     0.15717      1       NaN       -0.0102      1       NaN      NaN      NaN      NaN        -12.121         1.1637     0.99663      0.0261      0.0161     NaN              -242.37             -4.4919    -1.2962     NaN                      17.059                      388.73    391.61     0.1       0      316.17    7.2045    7.2568     0.1       0      0.0912    2.1015    2.1171    -1.7       0       NaN      NaN      NaN      NaN       9          283.64        283.54    1.0345e+05    1.2676    1009.2    0.0228       0.0102     0.0057     745.5    1256.2    0.00449    59.343    510.75    275.92       -0.15911        -1.2705    0.15138       1.2886        4.24e-16    -0.0142     1.2887     3.3667    77.138                  263.12                    NaN      NaN       0.1146       0.1211      10.566     2.5894     -1.8143    -0.0868        1        235.34        103       217       444       831     1794      7645                              0.0165                            1.0076      -12.2     1.011      6.9526    1.0723     0.41505    1.0723     0.15586    1.0723     -0.00491    1.3468     NaN       NaN            8e+08          8e+08     8e+08     8e+08          8e+08     8.011e+08    8e+08     8e+08     80100     80100       80        81        18        15        2         13        18         9        0        NaN                NaN                NaN       NaN       NaN       NaN       NaN       NaN       NaN       NaN                 0                  0         0         0                  0                  0         0         0         0         0         0         0         0         0         0         0       17778     17778     17778     17778         NaN             100          0.13076      0.0369     0.0746     0.0403    0.000594    20.289    9.46e-08     NaN       -0.00954       0.000415     0.15586    -4.91e-06     NaN           283.86           0       389.15    7.3729    3.0325     103.8    2.0948    1.0152e+05    42.366
    {'2023-01-09T170000_AIU-1485.ghg'}    01/09/0023    {'17:30'}    9.729     0      18000    18000                   0.0042                  1       NaN      5.7231      2       NaN      -2.8692      1       NaN      -0.2457      1       NaN     -0.0642      1       NaN      -0.00367      1       NaN      NaN      NaN      NaN        -42.241        -9.2783    -0.34004    -0.20758      0.0021     NaN               -853.1             -15.181    -4.5823     NaN                      17.166                      388.25    391.21    -0.6       0      305.47    6.9089     6.957    -0.6       0      0.0922    2.1045    2.1206    -2.1       0       NaN      NaN      NaN      NaN       9          282.86        281.48    1.0347e+05    1.2773      1009    0.0226     -0.00416     0.0055    715.05    1093.9    0.00431    65.368    378.83    275.33        0.19319       -0.88732    0.12718      0.91694        2.29e-16    -0.0497    0.91828     1.4566    57.717                  282.37                    NaN      NaN       0.0573       0.0288     -2.9419    -9.3002     -1.9946     0.0774        1         100.4         45        78       125       184      285       602                             0.00391                            1.0741     5.2987    1.0487     -2.9055    1.0548    -0.46602    1.0548      -0.065    1.0548     -0.00481    1.0889     NaN       NaN            8e+08          8e+08     8e+08     8e+08          8e+08     8.001e+08    8e+08     8e+08     80000     80000       80        81        18         6        1          4         0        12        0        NaN                NaN                NaN       NaN       NaN       NaN       NaN       NaN       NaN       NaN                 0                  0         0         0                  0                  0         0         0         0         0         0         0         0         0         0         0       18000     18000     18000     18000         NaN             100           0.0136      0.0379    0.00614    0.11397    0.000952    17.661    8.23e-08     NaN        0.00411      -0.000466      -0.065    -4.81e-06     NaN           281.95           0       388.86    7.5936    3.4526    103.78    2.0979    1.0155e+05    42.044
    {'2023-01-09T173000_AIU-1485.ghg'}    01/09/0023    {'18:00'}    9.749     0      18000    18000                 0.000491                  1       NaN      0.0756      2       NaN       2.2866      1       NaN      -0.0281      2       NaN      0.0511      1       NaN      2.23e-06      1       NaN      NaN      NaN      NaN        -36.517        -5.8353     0.76599    -0.13033     0.00283     NaN              -989.78             -17.096     -5.318     NaN                      17.329                      389.33    392.35    -0.6       0      299.31    6.7245    6.7701     0.6       0      0.0931    2.1086    2.1249    -1.3       0       NaN      NaN      NaN      NaN       9          281.07        279.71    1.0351e+05    1.2859    1008.9    0.0225      0.00331    0.00539    696.25    969.52    0.00419    71.814    273.27    274.96        0.21159       -0.26596     0.0588      0.34491       -6.19e-17    -0.0571    0.34961    0.94274    31.496                  308.33                    NaN      NaN       0.0195       0.0209     -8.8214    -3.1015      0.0331    0.00298        1        185.49         83       144       233       343      534      1140                            0.000429                            1.1451    0.18896    1.0968      2.0548    1.1039     -0.0467    1.1039      0.0459    1.1039    -0.000155    1.1456     NaN       NaN            8e+08          8e+08     8e+08     8e+08          8e+08         8e+08    8e+08     8e+08     80000     80000       80        81         1         0        0          2         0         1        0        NaN                NaN                NaN       NaN       NaN       NaN       NaN       NaN       NaN       NaN                 0                  0         0         0                  0                  0         0         0         0         0         0         0         0         0         0         0       18000     18000     18000     18000         NaN             100           0.0297      0.0105    0.00147    0.79534     0.00722    33.623    9.67e-08     NaN       0.000146      -4.67e-05      0.0459    -1.55e-07     NaN           280.09           0       389.81    7.7078    3.6694    103.75    2.1019    1.0158e+05    41.785
    {'2023-01-09T180000_AIU-1485.ghg'}    01/09/0023    {'18:30'}     9.77     0      18000    18000                 0.000438                  1       NaN     -1.2536      0       NaN     -0.49682      0       NaN       0.0592      1       NaN     -0.0111      0       NaN      -0.00531      0       NaN      NaN      NaN      NaN        -38.084         1.1723      2.2123      0.0261     -0.0036     NaN              -1258.7             -21.685     -6.701     NaN                      17.587                      392.44    395.53     0.6       0         303    6.7613    6.8073    -0.6       0      0.0936    2.1035      2.12    -2.1       0       NaN      NaN      NaN      NaN       9          279.64        277.89    1.0354e+05    1.2947    1008.9    0.0223    -0.000718    0.00546    700.22    854.02    0.00422    81.991     153.8    275.04        0.10415       -0.00275    0.00168      0.10332       -7.04e-17    -0.0716    0.12569    0.38919    341.51                  358.39                    NaN      NaN       0.0184      0.00926     0.44324     61.727      2.5232    -0.0522        1        5.6053          2         5         9        16       32       109                            0.000412                            1.0627    -1.1358    1.1212    -0.26417    1.6903      0.0736    1.6903    -0.00589    1.6903    -0.000928    5.2186     NaN       NaN            8e+08          8e+08     8e+08     8e+08          8e+08         8e+08    8e+08     8e+08     81000     81000       81        81         2         9        0          0         0         0        0        NaN                NaN                NaN       NaN       NaN       NaN       NaN       NaN       NaN       NaN                 0                  0         0         0                  0                  0         0         0         0         0         0         0         0         0         0         0       18000     18000     18000     18000         NaN             100           0.0118       0.005    0.00168    0.14606     0.00763    17.434    6.13e-08     NaN       -0.00087       7.36e-05    -0.00589    -9.28e-07     NaN            278.3           0       392.99    7.8211    3.8806    103.71    2.0966     1.016e+05    40.409
    {'2023-01-09T183000_AIU-1485.ghg'}    01/09/0023    {'19:00'}    9.791     0      18000    18000                 0.000412                  1       NaN      1.9632      2       NaN       1.2987      1       NaN     -0.88109      1       NaN      0.0289      1       NaN     -0.000768      1       NaN      NaN      NaN      NaN        -25.038        -1.1225      3.5124      -0.025    -0.00132     NaN              -1097.2             -18.573    -5.7674     NaN                       17.89                      397.35    400.48    -0.6       0      302.84    6.7263    6.7719     0.6       0       0.094    2.1016    2.1182     2.1       0       NaN      NaN      NaN      NaN       9          278.41        276.69    1.0357e+05    1.3008    1008.9    0.0222      0.00187    0.00546    696.85    785.19     0.0042    88.749    88.339    274.97        0.10182       -0.10158     0.0218      0.14544       -1.42e-16    -0.0613    0.15784     0.5507    24.933                  314.76                    NaN      NaN       0.0178        0.009    -0.25643     -106.7      1.5117     0.0841        1        16.632          8        13        21        30       47        99                            0.000336                            1.2271     1.7659    1.1535      1.0462    1.1626    -0.85092    1.1626      0.0233    1.1626     -0.00121     1.217     NaN       NaN            8e+08          8e+08     8e+08     8e+08     8.0001e+08    8.0011e+08    8e+08     8e+08     80110     80110       81        81         7        24        0          4         1         4        0        NaN                NaN                NaN       NaN       NaN       NaN       NaN       NaN       NaN       NaN                 0                  0         0         0                  0                  0         0         0         0         0         0         0         0         0         0         0       18000     18000     18000     18000         NaN             100          0.00901     0.00707    0.00191    0.46931      0.0294    20.456    6.77e-08     NaN        0.00135      -0.000851      0.0233    -1.21e-06     NaN           277.08           0       397.87    7.8389    3.9175    103.67    2.0946    1.0162e+05    38.505

Note that although the textfile has varying-width date fields, the table has (much better) constant-width dates with leading zeros. Also note that the year 23 occured around two thousand years ago, which is an impressive feat of data collection (aparently Pliny the Elder was born that year).

In any case, lets copy the code from your comment, fix the date format (so that it actually matches your textfile's dates), and see what happens:

opt = detectImportOptions(fnm, 'VariableNamesLine',2, 'VariableUnitsLine',3, 'VariableNamingRule','preserve');
opt = setvartype(opt, 'time','duration');
opt = setvartype(opt, 'date','datetime');
opt = setvaropts(opt, 'time','InputFormat','hh:mm');
opt = setvaropts(opt, 'date','InputFormat', 'M/d/yy'); % !!!!!  FIXED  !!!!!
tbl = readtable(fnm,opt) % I don't see any NATs here:

tbl = 6×185 table
                 filename                  date     time      DOY     daytime    file_records    used_records      Tau       qc_Tau    rand_err_Tau       H       qc_H    rand_err_H       LE       qc_LE    rand_err_LE    co2_flux    qc_co2_flux    rand_err_co2_flux    h2o_flux    qc_h2o_flux    rand_err_h2o_flux    ch4_flux     qc_ch4_flux    rand_err_ch4_flux    none_flux    qc_none_flux    rand_err_none_flux    H_strg     LE_strg    co2_strg    h2o_strg    ch4_strg    none_strg    co2_v-adv    h2o_v-adv    ch4_v-adv    none_v-adv    co2_molar_density    co2_mole_fraction    co2_mixing_ratio    co2_time_lag    co2_def_timelag    h2o_molar_density    h2o_mole_fraction    h2o_mixing_ratio    h2o_time_lag    h2o_def_timelag    ch4_molar_density    ch4_mole_fraction    ch4_mixing_ratio    ch4_time_lag    ch4_def_timelag    none_molar_density    none_mole_fraction    none_mixing_ratio    none_time_lag    none_def_timelag    sonic_temperature    air_temperature    air_pressure    air_density    air_heat_capacity    air_molar_volume       ET        water_vapor_density      e         es      specific_humidity      RH       VPD       Tdew     u_unrot     v_unrot     w_unrot     u_rot       v_rot       w_rot     wind_speed    max_wind_speed    wind_dir     yaw      pitch    roll      u*         TKE         L        (z-d)/L    bowen_ratio      T*       model    x_peak    x_offset    x_10%     x_30%     x_50%     x_70%    x_90%      un_Tau     Tau_scf     un_H      H_scf      un_LE      LE_scf    un_co2_flux    co2_scf    un_h2o_flux    h2o_scf    un_ch4_flux    ch4_scf    un_none_flux    un_none_scf    spikes_hf    amplitude_resolution_hf    drop_out_hf    absolute_limits_hf    skewness_kurtosis_hf    skewness_kurtosis_sf    discontinuities_hf    discontinuities_sf    timelag_hf    timelag_sf    attack_angle_hf    non_steady_wind_hf    u_spikes    v_spikes    w_spikes    ts_spikes    co2_spikes    h2o_spikes    ch4_spikes    none_spikes    head_detect_LI-7200    t_out_LI-7200    t_in_LI-7200    aux_in_LI-7200    delta_p_LI-7200    chopper_LI-7200    detector_LI-7200    pll_LI-7200    sync_LI-7200    chopper_LI-7500    detector_LI-7500    pll_LI-7500    sync_LI-7500    not_ready_LI-7700    no_signal_LI-7700    re_unlocked_LI-7700    bad_temp_LI-7700    laser_temp_unregulated_LI-7700    block_temp_unregulated_LI-7700    motor_spinning_LI-7700    pump_on_LI-7700    top_heater_on_LI-7700    bottom_heater_on_LI-7700    calibrating_LI-7700    motor_failure_LI-7700    bad_aux_tc1_LI-7700    bad_aux_tc2_LI-7700    bad_aux_tc3_LI-7700    box_connected_LI-7700    mean_value_RSSI_LI-7200    mean_value_LI-7500     u_var      v_var      w_var     ts_var     co2_var     h2o_var    ch4_var     none_var    w/ts_cov    w/co2_cov    w/h2o_cov    w/ch4_cov    w/none_cov    air_t_mean    vin_sf_mean    co2_mean    h2o_mean    dew_point_mean    co2_signal_strength_7500_mean    ch4_mean    air_p_mean    rssi_77_mean
    __________________________________    ______    _____    _____    _______    ____________    ____________    ________    ______    ____________    _______    ____    __________    ________    _____    ___________    ________    ___________    _________________    ________    ___________    _________________    _________    ___________    _________________    _________    ____________    __________________    _______    _______    ________    ________    ________    _________    _________    _________    _________    __________    _________________    _________________    ________________    ____________    _______________    _________________    _________________    ________________    ____________    _______________    _________________    _________________    ________________    ____________    _______________    __________________    __________________    _________________    _____________    ________________    _________________    _______________    ____________    ___________    _________________    ________________    _________    ___________________    ______    ______    _________________    ______    ______    ______    ________    ________    _______    _______    _________    _______    __________    ______________    ________    ______    _____    ____    _______    _______    ________    _______    ___________    _______    _____    ______    ________    ______    ______    ______    _____    ______    ________    _______    _______    ______    ________    ______    ___________    _______    ___________    _______    ___________    _______    ____________    ___________    _________    _______________________    ___________    __________________    ____________________    ____________________    __________________    __________________    __________    __________    _______________    __________________    ________    ________    ________    _________    __________    __________    __________    ___________    ___________________    _____________    ____________    ______________    _______________    _______________    ________________    ___________    ____________    _______________    ________________    ___________    ____________    _________________    _________________    ___________________    ________________    ______________________________    ______________________________    ______________________    _______________    _____________________    ________________________    ___________________    _____________________    ___________________    ___________________    ___________________    _____________________    _______________________    __________________    _______    _______    _______    _______    ________    _______    ________    ________    ________    _________    _________    _________    __________    __________    ___________    ________    ________    ______________    _____________________________    ________    __________    ____________

    {'2023-01-09T160000_AIU-1485.ghg'}    1/9/23    16:30    9.687       1          17935           17935          0.0665      1           NaN         -14.738     1         NaN          26.778      1          NaN          0.0367         2                NaN           0.60063          1                NaN             0.00191         2                NaN              NaN           NaN                NaN                NaN        NaN         NaN         NaN         NaN       NaN        -401.12      -7.4227      -2.1283        NaN              16.96                387.3               390.11              0.2               0                313.85               7.1671               7.2188                0               0                  0.09               2.0783               2.0934              2.1               0                  NaN                   NaN                   NaN                NaN                9                 284.22              284.13          1.0345e+05        1.265            1009.2               0.0228            0.0389          0.00566           741.6      1307         0.00447         56.742    565.37    275.85      0.0297     -1.7682    0.21998     1.7818     6.68e-16    -0.0237      1.7819          3.8905         69.039     271.12     NaN     NaN     0.22929    0.30973      73.058    0.37449     -0.55036      -0.0503      0      186.89    -28.361     64.154    159.75    243.63    341.7    511.92      0.0659    1.0093     -13.106    1.0065      26.491    1.0251      0.48109      1.0251       0.59418      1.0251        0.00422     1.1024         NaN             NaN          8e+08               8e+08                8e+08             8e+08                     8e+08                   8e+08               8e+08                 8e+08             81110         81110             80                   80                4          10          1           27             6             7            0             NaN                NaN                 NaN             NaN              NaN                NaN                NaN                NaN               NaN            NaN                0                  0                 0              0                  0                    0                     0                    0                          0                                 0                             0                      0                     0                         0                         0                       0                     16028                  16028                  16028                   16028                      NaN                     100            0.21354    0.19176    0.21417     0.0283     0.00137    26.625     2.35e-07      NaN        -0.0103     0.000481     0.59418      4.22e-06       NaN          285.13           0          388.63      7.2342         2.7633                   103.81                 2.0718     1.0152e+05       42.415   
    {'2023-01-09T163000_AIU-1485.ghg'}    1/9/23    17:00    9.708       0          17903           17903          0.0166      1           NaN         -12.721     1         NaN          7.0114      1          NaN         -0.0921         1                NaN           0.15717          1                NaN             -0.0102         1                NaN              NaN           NaN                NaN            -12.121     1.1637     0.99663      0.0261      0.0161       NaN        -242.37      -4.4919      -1.2962        NaN             17.059               388.73               391.61              0.1               0                316.17               7.2045               7.2568              0.1               0                0.0912               2.1015               2.1171             -1.7               0                  NaN                   NaN                   NaN                NaN                9                 283.64              283.54          1.0345e+05       1.2676            1009.2               0.0228            0.0102           0.0057           745.5    1256.2         0.00449         59.343    510.75    275.92    -0.15911     -1.2705    0.15138     1.2886     4.24e-16    -0.0142      1.2887          3.3667         77.138     263.12     NaN     NaN      0.1146     0.1211      10.566     2.5894      -1.8143      -0.0868      1      235.34        103        217       444       831     1794      7645      0.0165    1.0076       -12.2     1.011      6.9526    1.0723      0.41505      1.0723       0.15586      1.0723       -0.00491     1.3468         NaN             NaN          8e+08               8e+08                8e+08             8e+08                     8e+08               8.011e+08               8e+08                 8e+08             80100         80100             80                   81               18          15          2           13            18             9            0             NaN                NaN                 NaN             NaN              NaN                NaN                NaN                NaN               NaN            NaN                0                  0                 0              0                  0                    0                     0                    0                          0                                 0                             0                      0                     0                         0                         0                       0                     17778                  17778                  17778                   17778                      NaN                     100            0.13076     0.0369     0.0746     0.0403    0.000594    20.289     9.46e-08      NaN       -0.00954     0.000415     0.15586     -4.91e-06       NaN          283.86           0          389.15      7.3729         3.0325                    103.8                 2.0948     1.0152e+05       42.366   
    {'2023-01-09T170000_AIU-1485.ghg'}    1/9/23    17:30    9.729       0          18000           18000          0.0042      1           NaN          5.7231     2         NaN         -2.8692      1          NaN         -0.2457         1                NaN           -0.0642          1                NaN            -0.00367         1                NaN              NaN           NaN                NaN            -42.241    -9.2783    -0.34004    -0.20758      0.0021       NaN         -853.1      -15.181      -4.5823        NaN             17.166               388.25               391.21             -0.6               0                305.47               6.9089                6.957             -0.6               0                0.0922               2.1045               2.1206             -2.1               0                  NaN                   NaN                   NaN                NaN                9                 282.86              281.48          1.0347e+05       1.2773              1009               0.0226          -0.00416           0.0055          715.05    1093.9         0.00431         65.368    378.83    275.33     0.19319    -0.88732    0.12718    0.91694     2.29e-16    -0.0497     0.91828          1.4566         57.717     282.37     NaN     NaN      0.0573     0.0288     -2.9419    -9.3002      -1.9946       0.0774      1       100.4         45         78       125       184      285       602     0.00391    1.0741      5.2987    1.0487     -2.9055    1.0548     -0.46602      1.0548        -0.065      1.0548       -0.00481     1.0889         NaN             NaN          8e+08               8e+08                8e+08             8e+08                     8e+08               8.001e+08               8e+08                 8e+08             80000         80000             80                   81               18           6          1            4             0            12            0             NaN                NaN                 NaN             NaN              NaN                NaN                NaN                NaN               NaN            NaN                0                  0                 0              0                  0                    0                     0                    0                          0                                 0                             0                      0                     0                         0                         0                       0                     18000                  18000                  18000                   18000                      NaN                     100             0.0136     0.0379    0.00614    0.11397    0.000952    17.661     8.23e-08      NaN        0.00411    -0.000466      -0.065     -4.81e-06       NaN          281.95           0          388.86      7.5936         3.4526                   103.78                 2.0979     1.0155e+05       42.044   
    {'2023-01-09T173000_AIU-1485.ghg'}    1/9/23    18:00    9.749       0          18000           18000        0.000491      1           NaN          0.0756     2         NaN          2.2866      1          NaN         -0.0281         2                NaN            0.0511          1                NaN            2.23e-06         1                NaN              NaN           NaN                NaN            -36.517    -5.8353     0.76599    -0.13033     0.00283       NaN        -989.78      -17.096       -5.318        NaN             17.329               389.33               392.35             -0.6               0                299.31               6.7245               6.7701              0.6               0                0.0931               2.1086               2.1249             -1.3               0                  NaN                   NaN                   NaN                NaN                9                 281.07              279.71          1.0351e+05       1.2859            1008.9               0.0225           0.00331          0.00539          696.25    969.52         0.00419         71.814    273.27    274.96     0.21159    -0.26596     0.0588    0.34491    -6.19e-17    -0.0571     0.34961         0.94274         31.496     308.33     NaN     NaN      0.0195     0.0209     -8.8214    -3.1015       0.0331      0.00298      1      185.49         83        144       233       343      534      1140    0.000429    1.1451     0.18896    1.0968      2.0548    1.1039      -0.0467      1.1039        0.0459      1.1039      -0.000155     1.1456         NaN             NaN          8e+08               8e+08                8e+08             8e+08                     8e+08                   8e+08               8e+08                 8e+08             80000         80000             80                   81                1           0          0            2             0             1            0             NaN                NaN                 NaN             NaN              NaN                NaN                NaN                NaN               NaN            NaN                0                  0                 0              0                  0                    0                     0                    0                          0                                 0                             0                      0                     0                         0                         0                       0                     18000                  18000                  18000                   18000                      NaN                     100             0.0297     0.0105    0.00147    0.79534     0.00722    33.623     9.67e-08      NaN       0.000146    -4.67e-05      0.0459     -1.55e-07       NaN          280.09           0          389.81      7.7078         3.6694                   103.75                 2.1019     1.0158e+05       41.785   
    {'2023-01-09T180000_AIU-1485.ghg'}    1/9/23    18:30     9.77       0          18000           18000        0.000438      1           NaN         -1.2536     0         NaN        -0.49682      0          NaN          0.0592         1                NaN           -0.0111          0                NaN            -0.00531         0                NaN              NaN           NaN                NaN            -38.084     1.1723      2.2123      0.0261     -0.0036       NaN        -1258.7      -21.685       -6.701        NaN             17.587               392.44               395.53              0.6               0                   303               6.7613               6.8073             -0.6               0                0.0936               2.1035                 2.12             -2.1               0                  NaN                   NaN                   NaN                NaN                9                 279.64              277.89          1.0354e+05       1.2947            1008.9               0.0223         -0.000718          0.00546          700.22    854.02         0.00422         81.991     153.8    275.04     0.10415    -0.00275    0.00168    0.10332    -7.04e-17    -0.0716     0.12569         0.38919         341.51     358.39     NaN     NaN      0.0184    0.00926     0.44324     61.727       2.5232      -0.0522      1      5.6053          2          5         9        16       32       109    0.000412    1.0627     -1.1358    1.1212    -0.26417    1.6903       0.0736      1.6903      -0.00589      1.6903      -0.000928     5.2186         NaN             NaN          8e+08               8e+08                8e+08             8e+08                     8e+08                   8e+08               8e+08                 8e+08             81000         81000             81                   81                2           9          0            0             0             0            0             NaN                NaN                 NaN             NaN              NaN                NaN                NaN                NaN               NaN            NaN                0                  0                 0              0                  0                    0                     0                    0                          0                                 0                             0                      0                     0                         0                         0                       0                     18000                  18000                  18000                   18000                      NaN                     100             0.0118      0.005    0.00168    0.14606     0.00763    17.434     6.13e-08      NaN       -0.00087     7.36e-05    -0.00589     -9.28e-07       NaN           278.3           0          392.99      7.8211         3.8806                   103.71                 2.0966      1.016e+05       40.409   
    {'2023-01-09T183000_AIU-1485.ghg'}    1/9/23    19:00    9.791       0          18000           18000        0.000412      1           NaN          1.9632     2         NaN          1.2987      1          NaN        -0.88109         1                NaN            0.0289          1                NaN           -0.000768         1                NaN              NaN           NaN                NaN            -25.038    -1.1225      3.5124      -0.025    -0.00132       NaN        -1097.2      -18.573      -5.7674        NaN              17.89               397.35               400.48             -0.6               0                302.84               6.7263               6.7719              0.6               0                 0.094               2.1016               2.1182              2.1               0                  NaN                   NaN                   NaN                NaN                9                 278.41              276.69          1.0357e+05       1.3008            1008.9               0.0222           0.00187          0.00546          696.85    785.19          0.0042         88.749    88.339    274.97     0.10182    -0.10158     0.0218    0.14544    -1.42e-16    -0.0613     0.15784          0.5507         24.933     314.76     NaN     NaN      0.0178      0.009    -0.25643     -106.7       1.5117       0.0841      1      16.632          8         13        21        30       47        99    0.000336    1.2271      1.7659    1.1535      1.0462    1.1626     -0.85092      1.1626        0.0233      1.1626       -0.00121      1.217         NaN             NaN          8e+08               8e+08                8e+08             8e+08                8.0001e+08              8.0011e+08               8e+08                 8e+08             80110         80110             81                   81                7          24          0            4             1             4            0             NaN                NaN                 NaN             NaN              NaN                NaN                NaN                NaN               NaN            NaN                0                  0                 0              0                  0                    0                     0                    0                          0                                 0                             0                      0                     0                         0                         0                       0                     18000                  18000                  18000                   18000                      NaN                     100            0.00901    0.00707    0.00191    0.46931      0.0294    20.456     6.77e-08      NaN        0.00135    -0.000851      0.0233     -1.21e-06       NaN          277.08           0          397.87      7.8389         3.9175                   103.67                 2.0946     1.0162e+05       38.505   

"For some reason, my date is converted to NaT and final datetime is nat as well."

And yet when we use the correct date format, it works just fine.

Tip for the future: always look at your data files. You will save yourself a lot of trouble.

[Benju Baniya]

Thank you so much, yes I was opening data using readtable. But even when I use exactly same code as you have listed, it changes my datetime to NaT. I tried this earlier as well.

fnm = 'LI7500_eddypro_LP_2023_JFM_full_output_2023-04-17T105102_adv.csv';

opt = detectImportOptions(fnm, 'VariableNamesLine',2, 'VariableUnitsLine',3, 'VariableNamingRule','preserve');

opt = setvartype(opt, 'time','duration');

opt = setvartype(opt, 'date','datetime');

opt = setvaropts(opt, 'time','InputFormat','hh:mm');

opt = setvaropts(opt, 'date','InputFormat','M/d/yy');

tbl = readtable(fnm,opt)

dt = tbl.date + tbl.time;

dt.Format = 'uuuu-MM-dd HH:mm:ss'

Would there be anything else that can go wrong? Sorry, I am new to matlab and trying to understand things.

[Stephen23]

"Would there be anything else that can go wrong?"

What version of MATLAB are you using?

Have you opened-and-saved the data file using any application (e.g. MS Excel)?

Please upload the exact data file that you are running your code on.

[Benju Baniya]

I am using Matlab R2022a. The complete data file is very heavy so I uploaded edited version. But I will add it here.

[Stephen23]

"The complete data file is very heavy so I uploaded edited version."

What application did you use the edit the CSV file? It changed the date format.

Here are the original dates:

So, not the same date format as the "edited" (i.e mangled) file that you uploaded to your question. Whatever app you used (perhaps some half-baked Apple "easy-to-use" application?) mangled the dates. In fact, we can even see that the dates in the original file match the units line, whereas the ones in your "edited" (i.e. mangled) file do not.

Anyway, lets try the code using your actual data file:

unzip LI7500_eddypro_LP_2023_JFM_full_output_2023-04-17T105102_adv.csv.zip
fnm = 'LI7500_eddypro_LP_2023_JFM_full_output_2023-04-17T105102_adv.csv';
opt = detectImportOptions(fnm, 'VariableNamesLine',2, 'VariableUnitsLine',3, 'VariableNamingRule','preserve');
opt = setvartype(opt, 'time','duration');
opt = setvartype(opt, 'date','datetime');
opt = setvaropts(opt, 'time','InputFormat','hh:mm');
%opt = setvaropts(opt, 'date','InputFormat','u-MM-dd'); % optional, the date format is unambiguous.
tbl = readtable(fnm,opt) % I don't see any NaT here:

tbl = 3509×185 table
                 filename                    date       time      DOY     daytime    file_records    used_records       Tau        qc_Tau    rand_err_Tau       H        qc_H    rand_err_H       LE       qc_LE    rand_err_LE    co2_flux     qc_co2_flux    rand_err_co2_flux     h2o_flux     qc_h2o_flux    rand_err_h2o_flux     ch4_flux      qc_ch4_flux    rand_err_ch4_flux    none_flux    qc_none_flux    rand_err_none_flux    H_strg     LE_strg    co2_strg    h2o_strg      ch4_strg      none_strg    co2_v-adv    h2o_v-adv    ch4_v-adv    none_v-adv    co2_molar_density    co2_mole_fraction    co2_mixing_ratio    co2_time_lag    co2_def_timelag    h2o_molar_density    h2o_mole_fraction    h2o_mixing_ratio    h2o_time_lag    h2o_def_timelag    ch4_molar_density    ch4_mole_fraction    ch4_mixing_ratio    ch4_time_lag    ch4_def_timelag    none_molar_density    none_mole_fraction    none_mixing_ratio    none_time_lag    none_def_timelag    sonic_temperature    air_temperature    air_pressure    air_density    air_heat_capacity    air_molar_volume        ET         water_vapor_density      e         es      specific_humidity      RH       VPD       Tdew      u_unrot      v_unrot       w_unrot       u_rot         v_rot         w_rot      wind_speed    max_wind_speed    wind_dir     yaw      pitch    roll       u*          TKE          L        (z-d)/L    bowen_ratio        T*        model    x_peak    x_offset    x_10%     x_30%     x_50%     x_70%    x_90%       un_Tau      Tau_scf      un_H      H_scf      un_LE      LE_scf    un_co2_flux    co2_scf    un_h2o_flux    h2o_scf    un_ch4_flux    ch4_scf    un_none_flux    un_none_scf    spikes_hf    amplitude_resolution_hf    drop_out_hf    absolute_limits_hf    skewness_kurtosis_hf    skewness_kurtosis_sf    discontinuities_hf    discontinuities_sf    timelag_hf    timelag_sf    attack_angle_hf    non_steady_wind_hf    u_spikes    v_spikes    w_spikes    ts_spikes    co2_spikes    h2o_spikes    ch4_spikes    none_spikes    head_detect_LI-7200    t_out_LI-7200    t_in_LI-7200    aux_in_LI-7200    delta_p_LI-7200    chopper_LI-7200    detector_LI-7200    pll_LI-7200    sync_LI-7200    chopper_LI-7500    detector_LI-7500    pll_LI-7500    sync_LI-7500    not_ready_LI-7700    no_signal_LI-7700    re_unlocked_LI-7700    bad_temp_LI-7700    laser_temp_unregulated_LI-7700    block_temp_unregulated_LI-7700    motor_spinning_LI-7700    pump_on_LI-7700    top_heater_on_LI-7700    bottom_heater_on_LI-7700    calibrating_LI-7700    motor_failure_LI-7700    bad_aux_tc1_LI-7700    bad_aux_tc2_LI-7700    bad_aux_tc3_LI-7700    box_connected_LI-7700    mean_value_RSSI_LI-7200    mean_value_LI-7500      u_var        v_var        w_var        ts_var      co2_var      h2o_var     ch4_var      none_var     w/ts_cov       w/co2_cov     w/h2o_cov      w/ch4_cov     w/none_cov    air_t_mean    vin_sf_mean    co2_mean    h2o_mean    dew_point_mean    co2_signal_strength_7500_mean    ch4_mean    air_p_mean    rssi_77_mean
    __________________________________    __________    _____    _____    _______    ____________    ____________    __________    ______    ____________    ________    ____    __________    ________    _____    ___________    _________    ___________    _________________    __________    ___________    _________________    ___________    ___________    _________________    _________    ____________    __________________    _______    _______    ________    _________    ___________    _________    _________    _________    _________    __________    _________________    _________________    ________________    ____________    _______________    _________________    _________________    ________________    ____________    _______________    _________________    _________________    ________________    ____________    _______________    __________________    __________________    _________________    _____________    ________________    _________________    _______________    ____________    ___________    _________________    ________________    ___________    ___________________    ______    ______    _________________    ______    ______    ______    _________    __________    __________    ________    ___________    _________    __________    ______________    ________    ______    _____    ____    ________    _________    ________    _______    ___________    __________    _____    ______    ________    ______    ______    ______    _____    ______    __________    _______    ________    ______    ________    ______    ___________    _______    ___________    _______    ___________    _______    ____________    ___________    _________    _______________________    ___________    __________________    ____________________    ____________________    __________________    __________________    __________    __________    _______________    __________________    ________    ________    ________    _________    __________    __________    __________    ___________    ___________________    _____________    ____________    ______________    _______________    _______________    ________________    ___________    ____________    _______________    ________________    ___________    ____________    _________________    _________________    ___________________    ________________    ______________________________    ______________________________    ______________________    _______________    _____________________    ________________________    ___________________    _____________________    ___________________    ___________________    ___________________    _____________________    _______________________    __________________    _________    _________    __________    ________    __________    _______    __________    ________    ___________    ___________    __________    ___________    __________    __________    ___________    ________    ________    ______________    _____________________________    ________    __________    ____________

    {'2023-01-09T160000_AIU-1485.ghg'}    2023-01-09    16:30    9.687       1          17935           17935          0.066506      1           NaN          -14.738     1         NaN          26.778       1         NaN         0.036721          2               NaN              0.60063          1               NaN             0.0019091         2                NaN              NaN           NaN                NaN                NaN        NaN         NaN          NaN            NaN       NaN        -401.12      -7.4227      -2.1283        NaN              16.96                387.3               390.11              0.2               0                313.85               7.1671               7.2188                0               0               0.089989              2.0783               2.0934              2.1               0                  NaN                   NaN                   NaN                NaN                9                 284.22              284.13          1.0345e+05        1.265            1009.2              0.022836           0.038921         0.0056556          741.6      1307         0.004471        56.742    565.37    275.85     0.029674       -1.7682       0.21998      1.7818     6.6837e-16     -0.02365       1.7819         3.8905         69.039     271.12     NaN     NaN      0.22929      0.30973      73.058    0.37449     -0.55036       -0.050347      0      186.89    -28.361     64.154    159.75    243.63    341.7    511.92      0.065891    1.0093      -13.106    1.0065      26.491    1.0251       0.48109     1.0251        0.59418     1.0251        0.004218    1.1024         NaN             NaN          8e+08                8e+08               8e+08             8e+08                     8e+08                   8e+08               8e+08                 8e+08             81110         81110             80                   80                4          10          1           27             6             7            0             NaN                NaN                 NaN             NaN              NaN                NaN                NaN                NaN               NaN            NaN                0                  0                 0              0                  0                    0                     0                    0                          0                                 0                             0                      0                     0                         0                         0                       0                     16028                  16028                  16028                   16028                      NaN                     100              0.21354      0.19176       0.21417    0.028299     0.0013737    26.625     2.3468e-07      NaN         -0.010266     0.00048109       0.59418      4.218e-06       NaN          285.13           0          388.63      7.2342         2.7633                   103.81                 2.0718     1.0152e+05       42.415   
    {'2023-01-09T163000_AIU-1485.ghg'}    2023-01-09    17:00    9.708       0          17903           17903          0.016647      1           NaN          -12.721     1         NaN          7.0114       1         NaN         -0.09208          1               NaN              0.15717          1               NaN             -0.010235         1                NaN              NaN           NaN                NaN            -12.121     1.1637     0.99663     0.026087       0.016078       NaN        -242.37      -4.4919      -1.2962        NaN             17.059               388.73               391.61              0.1               0                316.17               7.2045               7.2568              0.1               0               0.091231              2.1015               2.1171             -1.7               0                  NaN                   NaN                   NaN                NaN                9                 283.64              283.54          1.0345e+05       1.2676            1009.2              0.022787           0.010185         0.0056973          745.5    1256.2        0.0044944        59.343    510.75    275.92     -0.15911       -1.2705       0.15138      1.2886     4.2418e-16    -0.014208       1.2887         3.3667         77.138     263.12     NaN     NaN       0.1146       0.1211      10.566     2.5894      -1.8143       -0.086769      1      235.34        103        217       444       831     1794      7645      0.016521    1.0076        -12.2     1.011      6.9526    1.0723       0.41505     1.0723        0.15586     1.0723      -0.0049131    1.3468         NaN             NaN          8e+08                8e+08               8e+08             8e+08                     8e+08               8.011e+08               8e+08                 8e+08             80100         80100             80                   81               18          15          2           13            18             9            0             NaN                NaN                 NaN             NaN              NaN                NaN                NaN                NaN               NaN            NaN                0                  0                 0              0                  0                    0                     0                    0                          0                                 0                             0                      0                     0                         0                         0                       0                     17778                  17778                  17778                   17778                      NaN                     100              0.13076     0.036853      0.074588     0.04027    0.00059412    20.289     9.4637e-08      NaN        -0.0095365     0.00041505       0.15586    -4.9131e-06       NaN          283.86           0          389.15      7.3729         3.0325                    103.8                 2.0948     1.0152e+05       42.366   
    {'2023-01-09T170000_AIU-1485.ghg'}    2023-01-09    17:30    9.729       0          18000           18000         0.0041991      1           NaN           5.7231     2         NaN         -2.8692       1         NaN          -0.2457          1               NaN            -0.064194          1               NaN            -0.0036702         1                NaN              NaN           NaN                NaN            -42.241    -9.2783    -0.34004     -0.20758      0.0020976       NaN         -853.1      -15.181      -4.5823        NaN             17.166               388.25               391.21             -0.6               0                305.47               6.9089                6.957             -0.6               0               0.092204              2.1045               2.1206             -2.1               0                  NaN                   NaN                   NaN                NaN                9                 282.86              281.48          1.0347e+05       1.2773              1009              0.022618         -0.0041598         0.0055045         715.05    1093.9        0.0043096        65.368    378.83    275.33      0.19319      -0.88732       0.12718     0.91694     2.2942e-16    -0.049698      0.91828         1.4566         57.717     282.37     NaN     NaN     0.057337     0.028822     -2.9419    -9.3002      -1.9946        0.077447      1       100.4         45         78       125       184      285       602     0.0039094    1.0741       5.2987    1.0487     -2.9055    1.0548      -0.46602     1.0548      -0.065005     1.0548       -0.004812    1.0889         NaN             NaN          8e+08                8e+08               8e+08             8e+08                     8e+08               8.001e+08               8e+08                 8e+08             80000         80000             80                   81               18           6          1            4             0            12            0             NaN                NaN                 NaN             NaN              NaN                NaN                NaN                NaN               NaN            NaN                0                  0                 0              0                  0                    0                     0                    0                          0                                 0                             0                      0                     0                         0                         0                       0                     18000                  18000                  18000                   18000                      NaN                     100             0.013616     0.037882     0.0061448     0.11397    0.00095235    17.661     8.2254e-08      NaN         0.0041113    -0.00046602     -0.065005     -4.812e-06       NaN          281.95           0          388.86      7.5936         3.4526                   103.78                 2.0979     1.0155e+05       42.044   
    {'2023-01-09T173000_AIU-1485.ghg'}    2023-01-09    18:00    9.749       0          18000           18000        0.00049127      1           NaN         0.075623     2         NaN          2.2866       1         NaN        -0.028074          2               NaN             0.051071          1               NaN            2.2307e-06         1                NaN              NaN           NaN                NaN            -36.517    -5.8353     0.76599     -0.13033       0.002825       NaN        -989.78      -17.096       -5.318        NaN             17.329               389.33               392.35             -0.6               0                299.31               6.7245               6.7701              0.6               0               0.093107              2.1086               2.1249             -1.3               0                  NaN                   NaN                   NaN                NaN                9                 281.07              279.71          1.0351e+05       1.2859            1008.9              0.022467          0.0033094         0.0053936         696.25    969.52        0.0041943        71.814    273.27    274.96      0.21159      -0.26596       0.05881     0.34491    -6.1859e-17    -0.057117      0.34961        0.94274         31.496     308.33     NaN     NaN     0.019546     0.020854     -8.8214    -3.1015     0.033073       0.0029822      1      185.49         83        144       233       343      534      1140    0.00042902    1.1451      0.18896    1.0968      2.0548    1.1039     -0.046717     1.1039       0.045895     1.1039     -0.00015548    1.1456         NaN             NaN          8e+08                8e+08               8e+08             8e+08                     8e+08                   8e+08               8e+08                 8e+08             80000         80000             80                   81                1           0          0            2             0             1            0             NaN                NaN                 NaN             NaN              NaN                NaN                NaN                NaN               NaN            NaN                0                  0                 0              0                  0                    0                     0                    0                          0                                 0                             0                      0                     0                         0                         0                       0                     18000                  18000                  18000                   18000                      NaN                     100             0.029728      0.01051     0.0014705     0.79534     0.0072166    33.623     9.6708e-08      NaN        0.00014564    -4.6717e-05      0.045895    -1.5548e-07       NaN          280.09           0          389.81      7.7078         3.6694                   103.75                 2.1019     1.0158e+05       41.785   
    {'2023-01-09T180000_AIU-1485.ghg'}    2023-01-09    18:30     9.77       0          18000           18000        0.00043781      1           NaN          -1.2536     0         NaN        -0.49682       0         NaN         0.059249          1               NaN            -0.011077          0               NaN             -0.005309         0                NaN              NaN           NaN                NaN            -38.084     1.1723      2.2123     0.026139     -0.0035981       NaN        -1258.7      -21.685       -6.701        NaN             17.587               392.44               395.53              0.6               0                   303               6.7613               6.8073             -0.6               0                0.09363              2.1035                 2.12             -2.1               0                  NaN                   NaN                   NaN                NaN                9                 279.64              277.89          1.0354e+05       1.2947            1008.9              0.022315        -0.00071781           0.00546         700.22    854.02        0.0042172        81.991     153.8    275.04      0.10415    -0.0027482      0.001677     0.10332    -7.0428e-17    -0.071569      0.12569        0.38919         341.51     358.39     NaN     NaN     0.018389    0.0092592     0.44324     61.727       2.5232       -0.052189      1      5.6053          2          5         9        16       32       109    0.00041199    1.0627      -1.1358    1.1212    -0.26417    1.6903      0.073556     1.6903       -0.00589     1.6903     -0.00092836    5.2186         NaN             NaN          8e+08                8e+08               8e+08             8e+08                     8e+08                   8e+08               8e+08                 8e+08             81000         81000             81                   81                2           9          0            0             0             0            0             NaN                NaN                 NaN             NaN              NaN                NaN                NaN                NaN               NaN            NaN                0                  0                 0              0                  0                    0                     0                    0                          0                                 0                             0                      0                     0                         0                         0                       0                     18000                  18000                  18000                   18000                      NaN                     100             0.011841    0.0049979     0.0016799     0.14606     0.0076291    17.434     6.1298e-08      NaN       -0.00086954     7.3556e-05      -0.00589    -9.2836e-07       NaN           278.3           0          392.99      7.8211         3.8806                   103.71                 2.0966      1.016e+05       40.409   
    {'2023-01-09T183000_AIU-1485.ghg'}    2023-01-09    19:00    9.791       0          18000           18000         0.0004118      1           NaN           1.9632     2         NaN          1.2987       1         NaN         -0.88109          1               NaN             0.028923          1               NaN           -0.00076761         1                NaN              NaN           NaN                NaN            -25.038    -1.1225      3.5124       -0.025     -0.0013221       NaN        -1097.2      -18.573      -5.7674        NaN              17.89               397.35               400.48             -0.6               0                302.84               6.7263               6.7719              0.6               0               0.094042              2.1016               2.1182              2.1               0                  NaN                   NaN                   NaN                NaN                9                 278.41              276.69          1.0357e+05       1.3008            1008.9              0.022211          0.0018742         0.0054572         696.85    785.19        0.0041954        88.749    88.339    274.97      0.10182      -0.10158      0.021841     0.14544    -1.4239e-16    -0.061328      0.15784         0.5507         24.933     314.76     NaN     NaN     0.017793    0.0090007    -0.25643     -106.7       1.5117        0.084081      1      16.632          8         13        21        30       47        99     0.0003356    1.2271       1.7659    1.1535      1.0462    1.1626      -0.85092     1.1626       0.023301     1.1626      -0.0012072     1.217         NaN             NaN          8e+08                8e+08               8e+08             8e+08                8.0001e+08              8.0011e+08               8e+08                 8e+08             80110         80110             81                   81                7          24          0            4             1             4            0             NaN                NaN                 NaN             NaN              NaN                NaN                NaN                NaN               NaN            NaN                0                  0                 0              0                  0                    0                     0                    0                          0                                 0                             0                      0                     0                         0                         0                       0                     18000                  18000                  18000                   18000                      NaN                     100            0.0090146    0.0070742     0.0019126     0.46931      0.029392    20.456     6.7714e-08      NaN         0.0013457    -0.00085092      0.023301    -1.2072e-06       NaN          277.08           0          397.87      7.8389         3.9175                   103.67                 2.0946     1.0162e+05       38.505   
    {'2023-01-09T190000_AIU-1485.ghg'}    2023-01-09    19:30    9.812       0          17993           17993        0.00088213      1           NaN           -1.597     2         NaN         -3.5506       1         NaN         -0.85501          1               NaN            -0.079004          1               NaN              0.004516         0                NaN              NaN           NaN                NaN            -20.082    -8.2195      2.8835     -0.18289     -0.0062109       NaN        -1141.1      -18.399      -5.9166        NaN              18.14               401.37                404.4             -0.6               0                292.49               6.4715               6.5137             -0.6               0               0.094056              2.0929               2.1087             -2.1               0                  NaN                   NaN                   NaN                NaN                9                 277.65              275.73          1.0361e+05       1.3059            1008.7              0.022126         -0.0051194         0.0052707          670.7    733.76        0.0040361        91.406     63.06    274.44     0.057677     -0.026626      0.006188    0.063645    -8.5492e-17    -0.062905     0.089486        0.42657         4.7804     334.78     NaN     NaN      0.02599     0.010697     0.98271     27.842      0.44979       -0.046647      1      1.5769          1          1         3         4        9        27    0.00084667    1.0419      -1.6318    1.0737     -2.4625    1.4091      -0.52768     1.4091      -0.054793     1.4091       0.0015374    3.4036         NaN             NaN          8e+08                8e+08               8e+08             8e+08                     8e+08                   8e+08               8e+08                 8e+08             81010         81010             81                   81                0           0          0            0             0             0            0             NaN                NaN                 NaN             NaN              NaN                NaN                NaN                NaN               NaN            NaN                0                  0                 0              0                  0                    0                     0                    0                          0                                 0                             0                      0                     0                         0                         0                       0                     17951                  17951                  17951                   17951                      NaN                     100             0.015779    0.0042038     0.0014121     0.24452      0.040864    65.135     1.3092e-07      NaN        -0.0012388    -0.00052768     -0.054793     1.5374e-06       NaN          276.26           0           402.1      7.5188         3.3286                   103.64                  2.086     1.0165e+05       37.815   
    {'2023-01-09T193000_AIU-1485.ghg'}    2023-01-09    20:00    9.833       0          17952           17952        0.00058335      1           NaN           1.6716     1         NaN        -0.21861       1         NaN         -0.27064          1               NaN           -0.0048615          1               NaN            -0.0011844         1                NaN              NaN           NaN                NaN            -12.786     -4.841      2.5218     -0.10766     -0.0021456       NaN        -1139.6      -17.794       -5.851        NaN             18.343               404.87               407.87             -0.6               0                286.42               6.3219               6.3622              0.5               0               0.094179              2.0899               2.1054             -2.1               0                  NaN                   NaN                   NaN                NaN                9                 276.86              275.13          1.0363e+05       1.3091            1008.6              0.022072        -0.00031503         0.0051613         655.33    702.67        0.0039425        93.263    47.335    274.12    0.0021902     -0.010219    -0.0027318    0.010022     1.5085e-16    -0.062127      0.06293        0.33731         57.903     279.37     NaN     NaN     0.021109      0.01201    -0.50308    -54.385      -7.6465        0.059974      1      5.7448          3          4         7        11       17        38    0.00043249    1.3488       1.3437    1.2349     -0.2214    1.2489      -0.28272     1.2489     -0.0049235     1.2489      -0.0012647    1.3336         NaN             NaN          8e+08                8e+08               8e+08             8e+08                     8e+08                   8e+08               8e+08                 8e+08             81110         81110             81                   81                0           0          1            0             0             0            0             NaN                NaN                 NaN             NaN              NaN                NaN                NaN                NaN               NaN            NaN                0                  0                 0              0                  0                    0                     0                    0                          0                                 0                             0                      0                     0                         0                         0                       0                     17919                  17919                  17919                   17919                      NaN                     100            0.0064445     0.016329     0.0012478     0.49125      0.019387    2.4779     1.4636e-07      NaN         0.0010176    -0.00028272    -0.0049235    -1.2647e-06       NaN          275.42           0          405.28      7.3559         3.0258                   103.61                 2.0831     1.0167e+05       36.752   
    {'2023-01-09T200000_AIU-1485.ghg'}    2023-01-09    20:30    9.854       0          18000           18000        0.00068861      1           NaN          0.32765     2         NaN          0.5076       2         NaN         -0.38614          1               NaN             0.011282          2               NaN           -0.00066171         1                NaN              NaN           NaN                NaN            -11.126     -4.467      2.6942    -0.099287      0.0013956       NaN        -1120.9      -16.965      -5.7106        NaN             18.548               408.61               411.56             -0.6               0                280.72               6.1842               6.2227             -0.6               0               0.094491              2.0918                2.107             -2.1               0                  NaN                   NaN                   NaN                NaN                9                 276.09               274.6          1.0363e+05       1.3117            1008.5               0.02203         0.00073109         0.0050586         641.06    676.61        0.0038565        94.746    35.552    273.81      0.11393      0.046015     0.0094169     0.12321    -5.5865e-16    -0.060435      0.13723        0.37494         318.01     21.332     NaN     NaN     0.022912     0.012643     -3.2819    -8.3366       0.6455         0.01081      1      31.736         14         25        40        60       95       207    0.00055379    1.2435      0.30578    1.1648     0.41982    1.1745      -0.34695     1.1745      0.0093314     1.1745     -0.00064587    1.2321         NaN             NaN          8e+08             8.11e+08               8e+08             8e+08                     8e+08              8.1101e+08               8e+08                 8e+08             80100         80100             81                   81                0           0          0           25             7             1            0             NaN                NaN                 NaN             NaN              NaN                NaN                NaN                NaN               NaN            NaN                0                  0                 0              0                  0                    0                     0                    0                          0                                 0                             0                      0                     0                         0                         0                       0                     18000                  18000                  18000                   18000                      NaN                     100             0.010126     0.014181    0.00097834     0.13941      0.014691    22.248     2.1293e-07      NaN        0.00023114    -0.00034695     0.0093314    -6.4587e-07       NaN          274.81           0          408.89      7.1884         2.6997                   103.52                 2.0851     1.0167e+05       36.104   
    {'2023-01-09T203000_AIU-1485.ghg'}    2023-01-09    21:00    9.874       0          18000           18000         0.0017497      1           NaN          -1.8378     0         NaN          1.9429       1         NaN          0.31652          1               NaN             0.043171          1               NaN            -0.0061332         0                NaN              NaN           NaN                NaN            -7.0928    -2.7456      1.1806    -0.061006      0.0028366       NaN        -1262.8      -18.776      -6.4207        NaN             18.647               410.24                413.1              0.6               0                277.26               6.0997               6.1372             -0.6               0               0.094813              2.0958               2.1104              2.1               0                  NaN                   NaN                   NaN                NaN                9                 276.08              274.26          1.0365e+05       1.3135            1008.5                 0.022          0.0027975         0.0049962         632.38    660.47        0.0038036        95.746    28.095    273.62     0.065345     -0.011118    0.00082412    0.065587     -1.019e-16    -0.067719     0.094273        0.50327         349.66     350.22     NaN     NaN     0.036498     0.023399      2.3652     11.568     -0.94592       -0.038013      1      1.5447          1          1         2         4        8        27     0.0016986    1.0301      -1.6772    1.0393      1.6609    1.2006       0.32744     1.2006       0.036905     1.2006      -0.0027073    2.0905         NaN             NaN          8e+08                8e+08               8e+08             8e+08                     8e+08                   8e+08               8e+08                 8e+08             80110         80110             81                   81                0           0          0            0             0             0            0             NaN                NaN                 NaN             NaN              NaN                NaN                NaN                NaN               NaN            NaN                0                  0                 0              0                  0                    0                     0                    0                          0                                 0                             0                      0                     0                         0                         0                       0                     18000                  18000                  18000                   18000                      NaN                     100             0.032459     0.011407     0.0029321     0.50461      0.056285    15.458     2.0458e-07      NaN        -0.0012661     0.00032744      0.036905    -2.7073e-06       NaN          274.41           0          410.43      6.9113         2.1496                   103.53                 2.0891     1.0167e+05       35.916   
    {'2023-01-09T210000_AIU-1485.ghg'}    2023-01-09    21:30    9.895       0          18000           18000         0.0014221      1           NaN         -0.99764     2         NaN         0.12224       2         NaN          0.48728          2               NaN            0.0027148          2               NaN            -0.0034473         1                NaN              NaN           NaN                NaN            -10.695    -6.2912    -0.92625     -0.13972     -0.0016374       NaN        -1308.2      -18.894      -6.6686        NaN             18.622               408.96               411.75              0.6               0                268.96               5.9065               5.9416             -0.6               0               0.094929              2.0935               2.1078             -2.1               0                  NaN                   NaN                   NaN                NaN                9                 275.56              273.76          1.0364e+05        1.316            1008.4              0.021961         0.00017592         0.0048466         612.31    636.82        0.0036829        96.151     24.51    273.18    0.0060112     -0.023224    -0.0090975    0.022597     8.3553e-17    -0.070248     0.073793        0.37244         55.489     281.03     NaN     NaN     0.032874      0.01072      3.1835     8.5944      -8.1614        -0.02287      1      1.3436          1          1         2         4        7        23     0.0013739    1.0351      -0.9555    1.0379     0.13171    1.1751       0.45723     1.1751      0.0029251     1.1751      -0.0016257     1.924         NaN             NaN          8e+08                8e+08               8e+08             8e+08                     8e+08              8.0001e+08               8e+08                 8e+08             80100         80100             81                   81                0           2          0            0             0             4            0             NaN                NaN                 NaN             NaN              NaN                NaN                NaN                NaN               NaN            NaN                0                  0                 0              0                  0                    0                     0                    0                          0                                 0                             0                      0                     0                         0                         0                       0                     18000                  18000                  18000                   18000                      NaN                     100             0.012528    0.0077656     0.0011469     0.66353      0.051505     13.89     2.8134e-07      NaN       -0.00072006     0.00045723     0.0029251    -1.6257e-06       NaN          274.19           0          409.57      6.7835         1.8872                   103.56                 2.0869     1.0167e+05       35.688   
    {'2023-01-09T213000_AIU-1485.ghg'}    2023-01-09    22:00    9.916       0          18000           18000         0.0014573      1           NaN          -7.2311     1         NaN          18.594       1         NaN           14.925          1               NaN              0.41286          1               NaN              0.022999         1                NaN              NaN           NaN                NaN            -5.5231    -3.3179     -15.287     -0.07367      0.0038688       NaN        -976.11      -14.609      -5.2608        NaN              17.68               387.85               389.98              0.6               0                264.61               5.8048               5.8387             -0.6               0               0.095286              2.0989               2.1104              2.1               0                  NaN                   NaN                   NaN                NaN                9                 274.99               273.5          1.0365e+05       1.3174            1008.3              0.021937           0.026753         0.0047682         601.84    624.92        0.0036193        96.307     23.08    272.94      0.11682       0.23035    -0.0036965     0.25829    -3.3355e-16     -0.05521      0.26413        0.77832         276.89     62.706     NaN     NaN      0.03326     0.030829     0.45489     60.146     -0.38889        -0.16367      1      8.9684          4          8        15        26       51       175     0.0013832    1.0536      -5.8975    1.1052      11.595    1.6148        9.3613     1.6148        0.25745     1.6148       0.0050864    4.7009         NaN             NaN          8e+08                8e+08               8e+08             8e+08                     8e+08              8.0001e+08               8e+08                 8e+08             81110         81110             80                   81                0           0          0            0             7             0            0             NaN                NaN                 NaN             NaN              NaN                NaN                NaN                NaN               NaN            NaN                0                  0                 0              0                  0                    0                     0                    0                          0                                 0                             0                      0                     0                         0                         0                       0                     18000                  18000                  18000                   18000                      NaN                      98             0.052662    0.0081619    0.00083484     0.40734        5.6713    6767.4     3.8483e-07      NaN        -0.0044397      0.0093613       0.25745     5.0864e-06       NaN          273.59           0          387.89      5.4672        -2.4973                   99.839                 2.0924     1.0168e+05       34.324   
    {'2023-01-09T220000_AIU-1485.ghg'}    2023-01-09    22:30    9.937       0          17988           17988         0.0012592      2           NaN          -6.1722     1         NaN          21.634       1         NaN           14.185          1               NaN              0.48044          1               NaN             0.0033096         1                NaN              NaN           NaN                NaN             4.1531     4.5055     -29.311      0.10006      0.0024937       NaN        -966.55      -16.538      -5.8236        NaN             15.826               347.35               348.35             -0.6               0                270.78                5.943               5.9786             -0.6               0               0.095355              2.1024               2.1084              1.3               0                  NaN                   NaN                   NaN                NaN                9                 274.88              273.69          1.0368e+05       1.3168            1008.4              0.021948           0.031132         0.0048795         616.33    633.85        0.0037057        97.235    17.526    273.27       0.3191       0.30123      0.012391     0.43899     5.2876e-16    -0.061073      0.44322         1.0157         296.65     42.826     NaN     NaN     0.030924      0.03921     0.42844      63.86     -0.28531        -0.15032      1      48.404         21         42        81       142      278       958     0.0011963    1.0526      -4.8446    1.1041      13.348    1.6267        8.7831     1.6267        0.29642     1.6267      0.00079468      4.73         NaN             NaN          8e+08                8e+08               8e+08             8e+08                     8e+08              8.1101e+08               8e+08                 8e+08             81110         81110             80                   81                0           0          1            0             0             0            0             NaN                NaN                 NaN             NaN              NaN                NaN                NaN                NaN               NaN            NaN                0                  0                 0              0                  0                    0                     0                    0                          0                                 0                             0                      0                     0                         0                         0                       0                     17911                  17911                  17911                   17911                      NaN                      93             0.068459    0.0090683    0.00089321     0.42035        4.1664    9944.1     5.6978e-08      NaN        -0.0036486      0.0087831       0.29642     7.9468e-07       NaN           273.7           0          347.25      2.8767        -13.008                   93.394                 2.0957      1.017e+05       32.231   
    {'2023-01-09T223000_AIU-1485.ghg'}    2023-01-09    23:00    9.958       0          17856           17856        0.00064916      1           NaN          -0.2495     2         NaN             NaN     NaN         NaN              NaN        NaN               NaN                  NaN        NaN               NaN             0.0026906         1                NaN              NaN           NaN                NaN            -20.538     4837.6         NaN       107.33     -0.0055716       NaN            NaN      -13.439      -5.0805        NaN                NaN                  NaN                  NaN              NaN               0                252.42               5.5205               5.5511              NaN               0               0.095427              2.0946               2.0946             -2.1               0                  NaN                   NaN                   NaN                NaN                9                 273.91              272.73          1.0368e+05       1.3216            1008.1               0.02187                NaN         0.0045485         572.49    590.88        0.0034417        96.888    18.389    272.26     0.017137       0.11131    -0.0039623     0.11259    -1.4215e-16     -0.05324      0.12454        0.40155         258.75     80.793     NaN     NaN     0.022163     0.012033      3.9013     7.0131          NaN      -0.0084494      1      22.384         10         20        38        68      136       487    0.00063267    1.0261     -0.24221    1.0301         NaN         1           NaN          1            NaN          1       0.0015558    1.7738         NaN             NaN          8e+08                8e+08               8e+08             8e+08                     8e+08                   8e+08               8e+08                 8e+08             80010         80010             81                   81                0           2          0            0             0             0            0             NaN                NaN                 NaN             NaN              NaN                NaN                NaN                NaN               NaN            NaN                0                  0                 0              0                  0                    0                     0                    0                          0                                 0                             0                      0                     0                         0                         0                       0                     17427                  17427                  17427                   17427                      NaN                      73            0.0053874     0.016583     0.0020954      0.4636           NaN       NaN     1.1818e-07      NaN       -0.00018179            NaN           NaN     1.5558e-06       NaN          272.76           0          177.92     -1.5545        -13.579                   73.456                 2.0883      1.017e+05       34.358   
    {'2023-01-09T230000_AIU-1485.ghg'}    2023-01-09    23:30    9.979       0          18000           18000         0.0018207      0           NaN         -0.69881     1         NaN             NaN     NaN         NaN              NaN        NaN               NaN                  NaN        NaN               NaN             0.0015765         0                NaN              NaN           NaN                NaN            -12.345     2447.1         NaN       54.266      0.0023266       NaN            NaN      -12.715      -5.0103        NaN                NaN                  NaN                  NaN              NaN               0                243.18               5.3073               5.3356              NaN               0               0.095828              2.0979               2.0979              2.1               0                  NaN                   NaN                   NaN                NaN                9                 273.26              272.15          1.0367e+05       1.3245              1008              0.021824                NaN         0.0043821         550.38    566.36        0.0033085        97.177    15.987    271.72     0.098468      0.086816      0.011286     0.13163     1.3805e-16    -0.052285      0.14163        0.51575          298.6     40.347     NaN     NaN     0.037076     0.019331      6.5211     4.1956          NaN       -0.014117      1      11.298          5         10        19        34       69       249     0.0017737    1.0266     -0.68187    1.0248         NaN         1           NaN          1            NaN          1       0.0011678    1.5355         NaN             NaN          8e+08                8e+08               8e+08             8e+08                     8e+08              8.0001e+08               8e+08                 8e+08             80110         80110             81                   81                0           8          0            0             0             0            0             NaN                NaN                 NaN             NaN              NaN                NaN                NaN                NaN               NaN            NaN                0                  0                 0              0                  0                    0                     0                    0                          0                                 0                             0                      0                     0                         0                         0                       0                     18000                  18000                  18000                   18000                      NaN                      44             0.026252    0.0096428     0.0027671     0.27984           NaN       NaN     5.8923e-08      NaN       -0.00051071            NaN           NaN     1.1678e-06       NaN          272.03           0         -279.94      91.466         27.261                   42.634                 2.0917      1.017e+05       34.828   

Note that your statement "when originally it was in the format yyyy/MM/dd" is still incorrect: the actual date format uses hyphens, not forward slashes. Programming by guessing is not very efficient.

As I wrote earlier, always look at your data files. It will save you a lot of trouble. Really, look at them.

[Benju Baniya]

Excel. The first version was edited. The zipped file I just uloaded is original version from eddy pro software. And now I understanf excel might have changed something during edits.

[Stephen23]

"And now I understanf excel might have changed something during edits. "

The only reason to use MS Excel for editing a CSV file is if you want random, unpredictable, untraceable, unhelpful changes to your filedata without any warning. For all other purposes, avoid getting MS Excel anywhere near textfiles.

In any case, there is no "might have" here, whatever app you used definitely did change the date formats, as my previous comments and screenshots showed. Having mangled data files made it harder to help you.

Tip for the future: look at your text files in an actual text editor. Not in Excel (it changes your data).

Look. At. Your. Data. Files.

Answer 2

[KSSV]

T = readtable('https://in.mathworks.com/matlabcentral/answers/uploaded_files/1361583/LI7500_eddypro_LP_2023_JFM_full_output_2023-04-17T105102_adv.csv') ;

Warning: The DATETIME data was created using format 'MM/dd/uuuu' but also matched 'dd/MM/uuuu'.
To avoid ambiguity, supply a datetime format using SETVAROPTS, e.g.
opts = setvaropts(opts,varname,'InputFormat','MM/dd/uuuu');

Warning: Column headers from the file were modified to make them valid MATLAB identifiers before creating variable names for the table. The original column headers are saved in the VariableDescriptions property.
Set 'VariableNamingRule' to 'preserve' to use the original column headers as table variable names.

dates = T.(2) ; 
TimeStrings = T.(3) ;
times = datenum(TimeStrings);
t = table(dates,times);
dates = datetime(t.dates,'Format','MM/dd/yyyy HH:mm');
times = datetime(t.times,'ConvertFrom','datenum','Format','MM/dd/yyyy HH:mm:SS');
%Add dates to times.
fullt = dates+timeofday(times);
t.DatesNTimes = fullt;
iwant = t.(3)

iwant = 6×1 datetime array
   01/09/0023 16:30
   01/09/0023 17:00
   01/09/0023 17:30
   01/09/0023 18:00
   01/09/0023 18:30
   01/09/0023 19:00

[Benju Baniya]

This works. Thank you so much.

Answer 3

[Askic V]

I would also like to suggest a bit different approach:

T = readtable('https://in.mathworks.com/matlabcentral/answers/uploaded_files/1361583/LI7500_eddypro_LP_2023_JFM_full_output_2023-04-17T105102_adv.csv') ;

Warning: The DATETIME data was created using format 'MM/dd/uuuu' but also matched 'dd/MM/uuuu'.
To avoid ambiguity, supply a datetime format using SETVAROPTS, e.g.
opts = setvaropts(opts,varname,'InputFormat','MM/dd/uuuu');

Warning: Column headers from the file were modified to make them valid MATLAB identifiers before creating variable names for the table. The original column headers are saved in the VariableDescriptions property.
Set 'VariableNamingRule' to 'preserve' to use the original column headers as table variable names.

dates = string(T.(2));
times = string(T.(3));
dates_times = strcat(dates, " ", times);
C = datetime(dates_times, 'InputFormat', 'dd/MM/yyyy HH:mm')

C = 6×1 datetime array
   01-Sep-0023 16:30:00
   01-Sep-0023 17:00:00
   01-Sep-0023 17:30:00
   01-Sep-0023 18:00:00
   01-Sep-0023 18:30:00
   01-Sep-0023 19:00:00

[Benju Baniya]

Thank you so mcuh but this gives me error : Error using datetime

Unable to convert the text to datetime using the format 'dd/MM/yyyy HH:mm'.