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How to subtract Mean from Matrix along columns

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JFz
JFz am 16 Nov. 2017
Bearbeitet: John D'Errico am 16 Nov. 2017
Hi,
In subtraction, there is an example of subtract mean from matrix: A - mean(A) and it works well. But I have a matrix A of 15X1000, and I want to subtract the mean mean(A, 2) along the 1000 columns, how to do that? Thanks Jennifer

Akzeptierte Antwort

JFz
JFz am 16 Nov. 2017
With the above help, found that bsxfun works for versions before 2017a:
bsxfun(@minus, A, mean(A, 2))

Weitere Antworten (2)

KL
KL am 16 Nov. 2017
Bearbeitet: KL am 16 Nov. 2017
Just the same way, A-A_mean. Here's an example with 5 columns,
>>A = reshape(1:25,5,5) %dummydata
A =
1 6 11 16 21
2 7 12 17 22
3 8 13 18 23
4 9 14 19 24
5 10 15 20 25
>>A_mean = mean(A,2)
A_mean =
11
12
13
14
15
>>A = A-A_mean
A =
-10 -5 0 5 10
-10 -5 0 5 10
-10 -5 0 5 10
-10 -5 0 5 10
-10 -5 0 5 10
EDIT (thanks John)
and for older versions,
A = bsxfun(@minus,A,A_mean)
  3 Kommentare
JFz
JFz am 16 Nov. 2017
I tried the above but got this error: Error using - Matrix dimensions must agree.
I am using 2016a. I will have to change a lot of code to upgrade to 2017a successfully. Thanks, let me look at repmat and bsxfun.
JFz
JFz am 16 Nov. 2017
OK. bsxfun works! bsxfun(@minus, A, mean(A, 2))

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JFz
JFz am 16 Nov. 2017
Thanks to KL and John! Have a nice day!

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