MATLAB: Retime: apply different method for different columns

MATLAB

I have a timetable with column 2 temperature and column 3 rainfall. I want to apply mean for column 2 and variance for column 3. Can one this be done with one retime function application?

Best Answer

It is not currently possible to apply different methods for different columns using a single retime function. You may try this:

outputTable = [retime(inputTable(:,2),'hourly','mean'), retime(inputTable(:,3),'hourly', @(x) var(x))];

Related Solutions

MATLAB: ‘retime’ with multiple methods

If you want to return the product of the standard deviation and the mean for the data in each time period, something like this (which I have not tried) should work:

TT3 = retime(TT, 'hourly', @(x) std(x)*mean(x))

As stated on the documentation page for retime the method input may be a function handle, but if it is it "must return an output argument that is a scalar or a row vector, and must accept empty inputs."

If you want to apply multiple methods to the variables in your timetable see the "Apply Multiple Methods to Timetable" example on the documentation page to which I linked earlier.

MATLAB: Problem with retime function

It can be done in pieces. retime applies the same method to all timetable variables. You'll need to create new timetables (only containing the variables you need for each method) and call retime for each method you want to use (first value, max, min, last value, sum) . At the end, combine the smaller time tables together. See this example from the documentation.

If I were to do this with the table you show above, I'd do something like this.

% Create a timetable for each method only containing the variables that method is applied to
M15_open = M15(:,"Open");
M15_high = M15(:,"High");
M15_low = M15(:,"Low");
M15_close = M15(:,"Close");
M15_vol = M15(:,"Volume");
% Retime each timetable
H1_open = retime(M15_open,'hourly','firstvalue');
H1_high = retime(M15_high,'hourly','max');
H1_low = retime(M15_low,'hourly','min');
H1_close = retime(M15_close,'hourly','lastvalue');
H1_vol = retime(M15_vol,'hourly','sum');
% Combine the individual timetables back into a single time table
H1 = [H1_open H1_high H1_low H1_close H1_vol]

Best Answer

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MATLAB: ‘retime’ with multiple methods

MATLAB: Problem with retime function

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