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How to find the mean after every n columns?

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B.kun
B.kun 2015-3-4
评论： B.kun 2015-3-4
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.

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采纳的回答

Sean de Wolski
Sean de Wolski 2015-3-4
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,[]))).'

更多回答（1 个）

Giorgos Papakonstantinou
编辑：Giorgos Papakonstantinou 2015-3-4
NewMatrix = mymatrix(:,1:4:end);
Youranswer = nanmean(NewMatrix , 2);
  2 个评论
Sean de Wolski
Sean de Wolski 2015-3-4
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 2015-3-4
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).

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