How to find the mean after every n columns?

Hi all

In order to find the mean column-wise, I know that we should code as follows:

Answer = nanmean(mymatrix,2); %%mymatrix has many columns %%Answer gives 1 column

Now I have a matrix of size 770 rows x 5760 columns. But I would like to find the mean after EVERY 4 columns and store them in a new matrix. So my final answer matrix will have 770 rows x 1440 columns. How can I do that? Any help is appreciated!

Thank you.

Answer 1

[Sean de Wolski]

This could be done with a simple for-loop or a slightly trickier reshape:

% Simple data
x = repmat(1:16,3,1)
nrows = 4; % rows to mean
meanby4 = squeeze(nanmean(reshape(x.',nrows,size(x,2)./nrows,[]))).'

[B.kun]

Thank you! This works perfect! :)

Answer 2

[Giorgos Papakonstantinou]

NewMatrix = mymatrix(:,1:4:end);
Youranswer = nanmean(NewMatrix , 2);

[Sean de Wolski]

I think OP wants the mean of the first four columns, mean of the second four columns etc., not skipping 1:3, 5:7.

[B.kun]

Thank you. I tried this but it didn't give right results. (I guess it skipped my data in between every 1st and 4th column).