Clear Filters
Clear Filters

How to find the mean after every n columns?

1 view (last 30 days)
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.

Accepted Answer

Sean de Wolski
Sean de Wolski on 4 Mar 2015
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,[]))).'

More Answers (1)

Giorgos Papakonstantinou
Giorgos Papakonstantinou on 4 Mar 2015
Edited: Giorgos Papakonstantinou on 4 Mar 2015
NewMatrix = mymatrix(:,1:4:end);
Youranswer = nanmean(NewMatrix , 2);
  2 Comments
Sean de Wolski
Sean de Wolski on 4 Mar 2015
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
B.kun on 4 Mar 2015
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).

Sign in to comment.

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!