How can I average a matrix of 105108X6 constructed every 5 minutes measured data to 15 min?

Hello Matlab community,

I have a matrix (105108X6) of climate variables gathered every 5 minutes of one year, I wanna average this information every 15 minutes and store the info in a new matrix, how can I do that? I tried doing a loop like this:

dat_cal_15 = zeros(round(length(dat_cal)/3),1)
for i=1:round(length(dat_cal)/3)
    for a = 3*((i-1)+1)-2
        for b = 3*i
            dat_cal(i,1)= round(mean(dat_cal(a:b)));
        end
    end 
end

but is not working for all the columns....

thank you for your help

Answer 1

[KL]

I's suggest using a timetable.

https://www.mathworks.com/help/matlab/timetables.html

Frist convert your matrix to timetable using array2timetable,

https://www.mathworks.com/help/matlab/ref/array2timetable.html

 dat_cal_TT = array2timetable(X,'RowTimes',time_column_here)

and then use retime,

https://www.mathworks.com/help/matlab/ref/retime.html

 TT_15min_mean = retime(dat_cal_TT,min_15_time_vector,'mean')

create a time vector (min_15_time_vector) with your desired sample time.

[Gina Cabas]

hi KL, I did what you suggested and I got the error showed below. The thing is I have climate values in each column, for example, column 1 is temperature, column 2 is humidity....and so on, and I have this info every 5 minutes, I mean, the time step of each row is 5 min, this is still a good solution?? did I put right the command that you suggested?

dat_cal_TT = array2timetable(dat_cal,'RowTimes',5)
Error using array2timetable (line 52)
Row times must be datetime or duration vector with one time for each row in input timetable.

[KL]

So all your five columns contain data. Then you have to create a datetime vector and use it to create the timetable. For example,

 data = rand(10,5); %10 measurements of 5 variables

now create a datetime vector for the same length with the start and endtime of your measurements,

 dt = datetime([2017 12 06 10 00 00]):minutes(1):datetime([2017 12 06 10 10 00]); %10 minutes

now use it with array2timetable,

 TT = array2timetable(data,'RowTimes',dt);

[Gina Cabas]

Thank KL for your help, I got what I needed, and then, to be able to use the new dataset and have again an array matrix with data, should I use timetable2table function?

[KL]

I'm not sure what you mean but if you want to extract the values from the resulting timetable, you could probably use .Values property.

 TT.Values