Replace matrix entries in Matlab based on their value and their index

Question

In MATLAB, I want to replace those entries in a matrix that their values equal to their row index with one, and the others with zero.

For example

A = [3 1 4 2 2 5 1 3 3];

and I want to have

B = [0 1 0 1 1 0 0 1 1];

Is there any way to do so efficiently?

Rody Oldenhuis · Accepted Answer · 2016-11-08 12:30:43Z

Bit more generic:

MATLAB before R2016b:

B = bsxfun(@eq, A, (1:size(A,1)).');

MATLAB R2016b and later:

B = ( A == (1:size(A,1)).' );

User1551892 · Accepted Answer · 2016-11-08 12:18:29Z

1

k = size (A) ; for i = 1 : k(1) for j = 1 : k(2) if (A(i,j) == i ) A(i,j) = 1; else A(i,j) = 0 ; end end end

Alternative as per stewie suggestion:

bsxfun (@eq, A, [1,1,1;2,2,2;3,3,3])

answered Nov 8, 2016 at 12:13

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1 Comment

@StewieGriffin: It was my mistake that I did not read his question properly. However, I added some code based on your suggestion in my answer. Thanks