MATLAB: How i do loop over column

for loop

hi all,

I have a matrix with the dim of 978 * 744 which I want to loop over a number of a column with time step equal to 168 (hr/week) to have the final matrices of each week separately with the same number of rows 978

could anyone help me with, please?

thank you in advance.

Best Answer

If you want to do time-based calculation with your data, for example, weekly average or something I'd highly recommend using timetables (version 16b and above). Even for versions a bit older than that, use tables with datevec and then varfun.

Take a look at the examples on this page: https://www.mathworks.com/help/matlab/timetables.html

Related Solutions

MATLAB: How i do weekly average

Let data - your array [978 x 744].

For MATLAB >= R2016b (here week -> [Sun : Sat]):

Time = (datetime([2017 7 1 0 0 0]):hours(1):datetime([2017 7 31 23 0 0]))';
% or: Time = datetime(timeCopy);
TT = array2timetable(data','R',Time);
TT_out = retime(TT,'weekly','mean');

For MATLAB < R2016b ( here week -> [Mon : Sun]):

data = data';
Time = (datetime([2017 7 1 0 0 0]):hours(1):datetime([2017 7 31 23 0 0]))';
wd = rem(weekday(Time) + 5, 7) + 1;
ii = [true;diff(wd == 1) == 1];
g = cumsum(ii);
[r,c] = ndgrid(g,1:size(TT,2));
TT_out = [table(Time(ii),'V',{'Time'}),...
                 array2table(accumarray([r(:),c(:)],data(:),[],@mean))];

MATLAB: Daily 3d array to monthly- dealing with alternate days in a month and leap years – How to do it

You don't have another option than just hardcoding the number of days in a month. You can do this in a fancy way using the date functions in Matlab, or just look at a calender. The fact that you have 365 days means that you are dealing with a non-leap year, so February only has 28 days.

There are probably simpler ways to solve it, but you can easily convert this 3D matrix to a cell array, apply the function you already suggested to each cell and then convert back to a 3D matrix.

A=rand(720,360,365);%generate example array
month_lengths=[31 28 31 30 31 30 31 31 30 31 30 31];%non-leap year
B=mat2cell(A,size(A,1),size(A,2),month_lengths);%divide into 1 cell per month
B=cellfun(@(x) mean(x,3),B,'UniformOutput',false);%find mean for each month
B=cell2mat(B);%convert back to 3D array

Best Answer

Related Solutions

MATLAB: How i do weekly average

MATLAB: Daily 3d array to monthly- dealing with alternate days in a month and leap years – How to do it

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