In row mean of consecutive columns up to end

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.

Answer 1

[Akira Agata]

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);

[Image Analyst]

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.

Answer 2

[Roger Stafford]

A = rand(1,100);
M = mean(reshape(A,5,[]),1);

[Safi ullah]

In case of A=54×100, how can we modify the same code? For 1 row it works well. Thanks!

[Roger Stafford]

   M = squeeze(mean(reshape(A,54,5,[]),2));