# Replace values with zero and zero with values in matrix simultaneously

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Emma Kuttler on 15 Apr 2022
Answered: John D'Errico on 15 Apr 2022
Hi, I have a 1363x12 matrix called SwRailNodeDemand. The first column is consecutive integers, and the other eleven columns either have values that are either positive, negative, or zero. What I'd like to do is keep the first column as is, but for the other columns, simultaneously replace the zeroes with a value (100) and the nonzero values with zero. I think this has to happen simultaneously in order to not have a matrix of all zeroes.
Then, after these changes have ocurred, I'd like to return only the rows that have nonzero values in columns 2:11.
Here's an example:
SwRailNodeDemand =
[1 0 4 -5 0 6 8 -11 7 9 10 0
2 1 0 0 0 0 0 0 0 2 0 -3
3 3 4 1 1 0 0 0 0 0 0 -1
4 1 3 1 1 1 1 1 1 1 1 1]
NewMatrix =
[1 100 0 0 100 0 0 0 0 0 0 100
2 0 100 100 100 100 100 100 100 0 100 0
3 0 0 0 0 100 100 100 100 100 100 0]
Thanks!

John D'Errico on 15 Apr 2022
Easy.
SwRailNodeDemand = [1 0 4 -5 0 6 8 -11 7 9 10 0;
2 1 0 0 0 0 0 0 0 2 0 -3;
3 3 4 1 1 0 0 0 0 0 0 -1;
4 1 3 1 1 1 1 1 1 1 1 1];
NewMatrix = [SwRailNodeDemand(:,1),(~SwRailNodeDemand(:,2:end))*100]
NewMatrix = 4×12
1 100 0 0 100 0 0 0 0 0 0 100 2 0 100 100 100 100 100 100 100 0 100 0 3 0 0 0 0 100 100 100 100 100 100 0 4 0 0 0 0 0 0 0 0 0 0 0

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