Finding Reaction Time from DateStrings

I'm trying to obtain a reaction time for datestrings obtained during a behavioral experiment

the date string formats from the experiment log files look like this: 'year-month-day hour:minute:second.ms'

example: '2013-08-01 00:30:10:12345'

I have three different datestr's I would like to look at and work with (question, best and worst)

If someone did not respond to a question during the experiment the cell was left blank (reason for isempty check)

Below is a code I am trying to run after loading the log file and variables, but I can't seem to get it to work

Thank you in advance for any help or advice!!! :)

a=2 b=1 for i = 1:numel(version_id)

    if isempty(question_display_time{a}) == 1
        qDisp = 0
    else
    qDisp = datenum(question_display_time{a})
    if isempty(best_sentence_selection_t{a}) == 1
        bTime = 0
    else
    bTime = datenum(best_sentence_selection_t{a})
    if isempty(worst_sentence_selection_{a}) == 1
        wTime = 0
    else
    wTime = datenum(worst_sentence_selection_{a});
    end
    end
    end

 bRT(b) = bTime - qDisp
 wRT(b) = wTime - qDisp

 if bRT(b) >= wRT(b);
     respondedFirst{b} = {'Worst'};
     betweenTime(b) = bRT - wRT;
 else
     respondedFirst{b} = {'Best'};
     betweenTime(b) = wRT - bRT;
 end
 a=a+1;
 b=b+1;
end

xlswrite('RT.xls' ,bRT,'A1') xlswrite('RT.xls',wRT,'B1') xlswrite('RT.xls',respondedFirst,'C1') xlswrite('RT.xls',betweenTime,'D1')

Answer 1

[per isakson]

Try

    str = '2013-08-01 00:30:10:12345';
    num = datenum( str, 'yyyy-mm-dd HH:MM:SS:FFF' );

Doc says:

    FFF, Millisecond in three digits

if that isn't good enough one has to handle "12345" separately. Try

    cac = regexp( str, ':', 'split' );
    str2num(cac{end})/1e5

and

    dif = datenum(str,'yyyy-mm-dd HH:MM:SS:FFF') - datenum(str,'yyyy-mm-dd HH:MM:SS')

[Mary]

Thank you so much for the quick response! I'm still having some trouble with my code it other than datenum that'snot letting it run correctly.

I keep getting the following error when running this

a=2 b=1 for i = 1:numel(version_id)

    if isempty(question_display_time{a}) == 1
        qDisp = 0
    else
    qDisp = datenum(question_display_time{a},'yyyy-mm-dd HH:MM:SS.FFF')
    if isempty(best_sentence_selection_t{a}) == 1
        bTime = 0
    else
    bTime = datenum(best_sentence_selection_t{a},'yyyy-mm-dd HH:MM:SS.FFF')
    if isempty(worst_sentence_selection_{a}) == 1
        wTime = 0
    else
    wTime = datenum(worst_sentence_selection_{a},'yyyy-mm-dd HH:MM:SS.FFF');
    end
    end
    end

 bRT(b) = bTime - qDisp
 wRT(b) = wTime - qDisp

 if bRT(b) >= wRT(b);
     respondedFirst{b} = {'Worst'};
     betweenTime(b) = bRT - wRT;
 else
     respondedFirst{b} = {'Best'};
     betweenTime(b) = wRT - bRT;
 end
 a=a+1;
 b=b+1;
end

xlswrite('RT.xls' ,bRT,'A1') xlswrite('RT.xls',wRT,'B1') xlswrite('RT.xls',respondedFirst,'C1') xlswrite('RT.xls',betweenTime,'D1')

In an assignment A(I) = B, the number of elements in B and I must be the same.

Any ideas?

[per isakson]

I "cannot" run and debug your code. You should learn how to use the debugging features.

I would convert the script to a function, which I find easier to debug. Then, I would set

    >> dbstop if error

and run the function.

Here are some links on debugging in Matlab

• Debugging in MATLAB
• Debugging session
• Debugging Approaches

[Mary]

Sorry about that - I resolved the problem - (I wasn't calling an entire vector instead of just one piece)

I'm still having problems with the datestr though. I continually get back an error that it could not process datenum with this format datenum(worst_sentence_selection_{a},'yyyy-mm-dd HH:MM:SS.FFF')

I've tried pulling out just the second/millisecond information, but for some of these the change in on the hour (one selection made at 11:59 and the other at 12:00), so it's not accurately giving me a difference between times.

Thank you again for the help! Please let me know if you have any other ideas!

[per isakson]

My imagination fails me and I don't like guessing

• "worst_sentence_selection{a}" - please provide a couple of examples
• do you need the full precision? Is milliseconds - three digits enough?
• "one selection made at 11:59 and the other at 12:00" Don't you get one minute? What do you get? Examples please!

[Mary]

question_display_time best_sentence_selection and worst_sentence_selection

are all in the format 'yyyy-mm-dd HH:MM:SS.FFF'

- three digits of milliseconds would be plenty- it's just that MATLAB isn't taking that format in datenum (it errors everytime)

- If I try to take the date in a smaller format (for example) MM:SS.FFF it works - but I have the 11:59 - 12:00 problem, where it takes every hour as 00:MM:SS.FFF

sorry for the confusion

thank you again

[per isakson]

Which release of Matlab do you use? Examples like this

    str = '2013-08-01 00:30:10:12345';
    num = datenum( str, 'yyyy-mm-dd HH:MM:SS:FFF' );

works fine with R2013a (and several releases back, I'm positive).

However,

    str = '2013-08-01 00:30:10';
    num = datenum( str, 'yyyy-mm-dd HH:MM:SS:FFF' );

returns

    Error using datenum (line 179)
    DATENUM failed.
    Caused by:
        Error using dtstr2dtnummx
        Failed on converting date string to date number.

The date-string must match the full date-format. In this case there is nothing to match ":FFF"

"the 11:59 - 12:00 problem," What do you mean? Please, provide full examples like I do here.

[Mary]

I have formatting similar to above - except for ms, it's MM:SS.FFF instead of MM:SS:FFF. Do you think that could be making a difference (i've tried both colon and period formats)?

Thanks

[per isakson]

The format-string and the date-string must match! Either, ":" in both or "." in both.

This returns an error

    str = '2013-08-01 00:30:10:12345';
    num = datenum( str, 'yyyy-mm-dd HH:MM:SS.FFF' );

returns

    Error using datenum (line 179)
    DATENUM failed.
    Caused by:
        Error using dtstr2dtnummx
        Failed on converting date string to date number.

Your question contains, "'year-month-day hour:minute:second.ms' [...] example: '2013-08-01 00:30:10:12345'", which is in error. There is a "." between "second" and "ms", but in the corresponding position in the date-string there is a ":". I missed that.