Using vector as index columns in matrix rows, in Octave
Let's say I have a matrix A and a vector B. Is it possible to use the values ββin vector B as indices to select one value from each row in matrix A? Example:
A = [1, 2, 3;
4, 5, 6;
7, 8, 9;]
B = [1;3;1]
C = A(B) or C = A(:,B)
giving:
C = [1; 6; 7]
Of course, I could do it with a for loop, but with large matrices it will take a while. I would also like to use this to make a boolean matrix like this:
A = zeros(3,3) B = [1;3;1] A(B) = 1 A = [1, 0, 0; 0, 0, 1; 1, 0, 0]
Thanks for any advice you can give me.
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