Hello, I need help with: Replace elements in Vector A with those of vector B of the same position, only if they meet a certain condition, otherwise replace by a zero. Thanks

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MuluMe 2022-8-3

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评论： Jon 2022-8-3

I have Vectors A and B of the same length and a threshhold value:

Threshold = 4;
A = [3     7    1     3    10     3     4     1     5     5];
B = [5     3     6     1     6     3     5     4     9     4];

I want replace all values in A that are greater than threshold (A > Threshold) with values in B if they are less than the threshold (B < Threshold), otherwise make them zeros. In thi case, the new vector of A should be:

Thank you.

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MuluMe 2022-8-3

Am so grateful team, for your brilliant ideas. They have worked.

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Answer 1

Jon 2022-8-3

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编辑：Jon 2022-8-3

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I like @Torsten's one liner and use of the multiplication times the logical zeros to null out the values where B is greater than the threshold. Alternatively, you could do it like this in two lines and the logic is a little more obvious

Threshold = 4;
A = [3     7    1     3    10     3     4     1     5     5];
B = [5     3     6     1     6     3     5     4     9     4];
A(A>Threshold) = B(A>Threshold)
A = 1×10
     3     3     1     3     6     3     4     1     9     4
A(A>Threshold) = 0 % in case any of the B's we put in are over the threshold set them to zero
A = 1×10
     3     3     1     3     0     3     4     1     0     4

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Jon 2022-8-3

Good catch @Torsten You're right this approach does not work - thanks

Jon 2022-8-3

Thanks for accepting my answer, but I think actually @Torsten approach looks the closest to what you describe. I think you can click on the accepted answer and change it if you want.

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Answer 2

Torsten 2022-8-3

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编辑：Torsten 2022-8-3

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I kept the values in A unchanged that are less or equal to Threshold. If you also want to replace them by 0, take David's answer.

Threshold = 4;
A = [3     7    1     3    10     3     4     1     5     5];
B = [5     3     6     1     6     3     5     4     9     4];
A(A>Threshold) = B(A>Threshold).*(B(A>Threshold) < Threshold)
A = 1×10
     3     3     1     3     0     3     4     1     0     0

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Answer 3

David Hill 2022-8-3

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t=4;
A = [3     7    1     3    10     3     4     1     5     5];
B = [5     3     6     1     6     3     5     4     9     4];
idx=A>t&B<t;
A(idx)=B(idx);
A(~idx)=0
A = 1×10
     0     3     0     0     0     0     0     0     0     0