Convert a vector to a binary matrix

 y = [1; 1; 2; 3; 4; 4];

I want to convert this to a matrix such that in each row the corresponding element is 1 and the rest are zero.

 y = [1 0 0 0;
      1 0 0 0;
      0 1 0 0;
      0 0 1 0;
      0 0 0 1];

What is the best way to do this preferably without using loops?

Answer 1

[Guillaume]

Use sub2ind to transform row/column coordinates in linear indices and use that linear index to assign to your destination matrix:

y = [1; 1; 2; 3; 4; 4];
newy = zeros(numel(y), max(y));
newy(sub2ind(size(newy), 1:numel(y), y')) = 1

Answer 2

[Pawel Jastrzebski]

With LOOP:

y = [1; 1; 2; 3; 4; 4];

nRow = length(y);
nCol = max(y);

A = zeros(nRow,nCol);

for i=1:nRow
A(i,y(i)) = 1; 
end

A

WITHOUT LOOP:

y1 = [1; 1; 2; 3; 4; 4];
nRow1 = length(y1);
nCol1 = max(y1);
A1 = zeros(nRow1,nCol1); 

index = (y1-1).*nRow1+(1:nRow1)';
A1(index) = 1;
A1

[Birdman]

What is the best way to do this preferably without using loops?

Do not use loop.

[Utkarsh Barsaiyan]

Yes, this is the basic thing. I am looking for an answer that does it without using loops. For eg., I create an array of zeros of the corresponding size then make all the elements corresponding to the columns in y to be 1.