I have an index matrix. idx = [1 5 ; 3 7 ] The goal is to get a matrix like this: 1 0 0 0 0 1 0 0 1 0 0 0 0 1 Indexing the matrix like a(idx) = 1; doesn't work. Right now I use a loop, but I am not sure if this is the best way.

Matrix Indexing

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Joerg on 4 Feb 2011

I have an index matrix.

idx = [1 5 ; 3 7 ]

The goal is to get a matrix like this:

Indexing the matrix like

a(idx) = 1;

doesn't work. Right now I use a loop, but I am not sure if this is the best way.

Matt Fig on 4 Feb 2011

A = zeros(max(idx(:)),size(idx,1));
A(sub2ind(size(A),idx,cumsum(ones(size(idx))))) = 1

Joerg on 7 Feb 2011

Thanks!

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