MATLAB: How to select rows based on the value in a specific column and calculate the mean of those rows for all other columns to create a new table containing just the means

MATLABselect rows

I have a table array 3152×25 containing data for variables that are monitored over time. In column 25 I have a vaiable 'elapsedHr' for the calculated elapsed time in hours from 0 to 72, with 40+ rows corresponding to each hourly time point. I would like to calculate the mean value of each column variable (columns 2 to 20) for each of the 73 time points and generate a new table containing this data.

Best Answer

TT = table2timetable(Port1a(:,2:end),'RowTime',datetime(Port1a{:,1}));
out = varfun(@mean,TT(:,[1:20,end]),'GroupingVariables','elapsedHr');

or just for your case

out = varfun(@mean,Port1a(:,[2:20,end]),'GroupingVariables','elapsedHr');

Related Solutions

MATLAB: How to convert 3 hourly data into a 6 hourly data

In R2016b

[m,n,k] = size(A);
t = hours(0:3:(k-1)*3);
Ar = reshape(A,m,[]);
TT = table2timetable(array2table(Ar),'RowTime',t(:));
T1 = retime(TT,TT.Time(1:2:end),'mean');
out = reshape(T1{:,:},[],n,k);

add:

[m,n,k] = size(A);
t = hours((0:m-1)*3)';
o1 = varfun(@mean,array2table([floor(t / hours(6)) + 1,reshape(A,m,[])]),...
                                                 'GroupingVariables','Var1');
out = reshape(o1{:,3:end},[],n,k);

MATLAB: Best way to lookup values in table…

As it turns out, the above code referencing tables took about 8 seconds to run, after replacing all the tables to look up from arrays/matrices then add the calc'd array to the table it now takes less than 1/3 of a second, much better.

For reference to anyone else,

            t2=t{:,:};
            Hrs = HourlyProfile.Hr;
            Mos = HourlyProfile.Mo;
            %tic
            for i=1:size(HourlyProfile,1)
                Gen(i) = t2(Hrs(i)+1, Mos(i));
            end
            %toc
            HourlyProfile.Gen = Gen;

Best Answer

Related Solutions

MATLAB: How to convert 3 hourly data into a 6 hourly data

MATLAB: Best way to lookup values in table…

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