How can I convert an Array with row values to a binary Matrix?

Hi,

I have an array A containing natural numbers. The indices of the array represent the current column and the numbers itself represent the rows of a matrix M. Now I want to set the matrix at one for the corresponding values in the array.

Like the following code

A = [2 3 3 4 5 4 3];
M = zeros(length(A));
for i= 1:length(A)
    M(A(i),i) = 1;
end
M

M = 7×7

0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 1 0 0 0 1 0 0 0 1 0 1 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

I know that using loops in Matlab can be very slow and I want a faster way of computing this, since the array in my project has a length of 60000. Is there a way to run compute this faster?

Answer 1

[Cris LaPierre]

Porabbly with sub2ind.

A = [2 3 3 4 5 4 3];
M = zeros(length(A));

Col = 1:length(A);
ind = sub2ind(size(M),A,Col);
M(ind) = 1

M = 7×7

0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 1 0 0 0 1 0 0 0 1 0 1 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

[Kjell]

It worked thank you