How to take an average by date

I have a set of files, each with data from a trial of an experiment. I need to run a function on each file to summarize the data from each file (in a percentage). I then need to group the files by date (of the data collection) and average the percentages for each day, so that I have one total percentage for each day of data. I load the files using 'dir' and I have the function written to get the percentage in each file, but I cannot figure out how to group the files by date to take the average of each day. I eventually want to be able to plot the data with one point for each day that I have files from. Any help would be appreciated!

Answer 1

[Peter Perkins]

Put your data in a timetable, then use retime, with 'mean'. It's one line:

>> tt = timetable(datetime(2018,3,23,1:12:71,0,0)',rand(6,1))
tt =
  6×1 timetable
            Time             Var1  
    ____________________    _______
    23-Mar-2018 01:00:00    0.95717
    23-Mar-2018 13:00:00    0.48538
    24-Mar-2018 01:00:00    0.80028
    24-Mar-2018 13:00:00    0.14189
    25-Mar-2018 01:00:00    0.42176
    25-Mar-2018 13:00:00    0.91574
>> ttMean = retime(tt,'daily','mean')
ttMean =
  3×1 timetable
            Time             Var1  
    ____________________    _______
    23-Mar-2018 00:00:00    0.72127
    24-Mar-2018 00:00:00    0.47108
    25-Mar-2018 00:00:00    0.66875

Answer 2

[KSSV]

You have dates in hand.......convert the dates into datevec. From these you can sort them. Read about datevec.

[a p]

so after using datevec here is what i got:

        2018           2           9
        2018           2           9
        2018           2           9
        2018           2           9
        2018           2           9
        2018           2           9
        2018           2           9
        2018           2           9
        2018           2           9
        2018           2           9
        2018           2           9
        2018           2           9
        2018           2           9
        2018           3          12
        2018           3          12
        2018           3          12
        2018           3          12
        2018           3          13
        2018           3          13
        2018           3          13
        2018           3          13
        2018           3          13
        2018           3          13
        2018           3          13
        2018           3          13
How do I group my files according to date in order to average the values for each day?

[KSSV]

clc; clear all ;
dates = [ 2018           2           9
        2018           2           9
        2018           2           9
        2018           2           9
        2018           2           9
        2018           2           9
        2018           2           9
        2018           2           9
        2018           2           9
        2018           2           9
        2018           2           9
        2018           2           9
        2018           2           9
        2018           3          12
        2018           3          12
        2018           3          12
        2018           3          12
        2018           3          13
        2018           3          13
        2018           3          13
        2018           3          13
        2018           3          13
        2018           3          13
        2018           3          13
        2018           3          13] ;

% 
months = dates(:,2) ;
dayes = dates(:,3) ;

[c,ia,ib] = unique(months) ;
iwant = cell(length(c),1) ;
for i = 1:length(c)
    iwant{i} = dates(ib==i,:) ;
    iwant{i}
end