In row mean of consecutive columns up to end

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Hello everyboby, I have a matrix A=1×100. Now I want to find the mean of row for each consecutive five columns up to last. that is Answer=mean(1-5 columns), mean(6-10 columns), mean(11-15columns),…. mean(96-100 columns). As a result I want to get one row vector containing 20 columns. I tried as mean(A(1,1:5:100)) but not get the desired result.

Answers (2)

Akira Agata
Akira Agata on 28 Feb 2017
Edited: Akira Agata on 28 Feb 2017
I think splitapply function will help. Please try the following code.
A = rand(1,100); % Example
group = reshape(repmat([1:20],5,1),1,100);
result = splitapply(@mean,A,group);
  1 Comment
Image Analyst
Image Analyst on 28 Feb 2017
Cool! I was going to suggest blockproc() as an alternative, but that's only in the Image Processing Toolbox. It looks like they've put this general purpose function, splitapply(), into base MATLAB since version R2015b. (I guess I should read or remember the release notes.) It could even be applied to do any arbitrary function on arbitrary-sized arrays using any group criteria that you want.

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Roger Stafford
Roger Stafford on 28 Feb 2017
Edited: Image Analyst on 28 Feb 2017
A = rand(1,100);
M = mean(reshape(A,5,[]),1);
  2 Comments
Safi ullah
Safi ullah on 28 Feb 2017
Edited: Image Analyst on 28 Feb 2017
In case of A=54×100, how can we modify the same code? For 1 row it works well. Thanks!
Roger Stafford
Roger Stafford on 28 Feb 2017
M = squeeze(mean(reshape(A,54,5,[]),2));

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