How do I get the mean of always 4 columns

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Antonio Melieni
Antonio Melieni 2019-4-15
评论： Antonio Melieni 2019-4-17
Hi,
I have a 527040 x 16 double array
I need the row mean of always 4 clomuns
So I need the row mean of column 1:4 5:8 9:12 13:16
So I want the mean([1:4],2) and mean([5:8],2)
but i dont want to wirte it down in that way. I need an more automatic way to do it
any ideas?

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madhan ravi
madhan ravi 2019-4-15
编辑：madhan ravi 2019-4-15
AA=permute(reshape(A.',4,1,[]),[2,1,3]); % where A is size 527040 X 16
AAA=squeeze(mean(AA));
% if you want to reshape it as matrix then
% reshape(AAA,size(A,1),[]) %% edit removed transpose
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Matt J
Matt J 2019-4-15
Both the permute operation and the transpose operation allocate arrays the same size as A. sepblockfun avoids this.
madhan ravi
madhan ravi 2019-4-15
@Antonio:Matt‘s file exchange is Perfect why not use his solution then?

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更多回答（1 个）

Matt J
Matt J 2019-4-15
编辑：Matt J 2019-4-15
One way is using sepblockfun, downloadable from here
https://www.mathworks.com/matlabcentral/fileexchange/48089-separable-block-wise-operations
Then you would do,
result = sepblockfun(yourArray, [1,4],'mean');
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Catalytic
Catalytic 2019-4-15
编辑：Catalytic 2019-4-15
@Antonio,
The only way I can Matt J's one line solution as being "too complicated" is that this is homework. So, you're not allowed to use third-party routines like sepblockfun as is, and it is a tedious matter for you to try to decipher what it is doing and adapt it to your assignment.
Antonio Melieni
Antonio Melieni 2019-4-17
@Matt
Thanks for your function and your help.
Will use your sultion :)

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