Using a column vector of indices to replace values in a matrix

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Teddy Fisher
Teddy Fisher on 13 Dec 2019
Commented: sruizpp on 18 Nov 2020
I have a column vector, C, (55x1 double) which are the indices of my values of interest in Matrix, M which is 370x29 double.
I want to replace all the values in M that are not these values of interest with 0.
I am trying to use C to index into M and replace ~C with 0.
However when I try
all it does is change all the values in M to just different values and I'm not sure why.
When I try to create a new Matrix
N=M(~C==0) it returns a columnn vector with just the first 55 values in the first column of M.
Does anyone know how I can replace all the elements in M that are not listed in C with 0? I want my output to be another 370x29 double matrix.
Fangjun Jiang
Fangjun Jiang on 13 Dec 2019
with this comments, the answer below should provide one solution.

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Accepted Answer

More Answers (1)

Guillaume on 13 Dec 2019
Edited: Guillaume on 13 Dec 2019
Well, now you have explained how you got C, a much simpler method than the accepted one is not to create C and use:
M(~R) = 0; %that's all that is needed!
As usual in matlab, find is completely unnecessary and what you were trying to do initially would have worked had you kept your original logical vector.

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