2D logical matrix from vector of coordinates (Basic matlab)

Question

I have a 2D vector which contains the coordinates which I want to represent as True or one in a matrix with dimensions nxm. Can I build this matrix without a loop?

Answer 1

Your assignment to points is syntactically incorrect, it should be:

points=[1,30,8;1,20,7];

The solution to you problem lies in converting subscripts to linear indices with sub2ind:

grid(sub2ind(size(grid),points(1,:),points(2,:)))=1

Answer 2

I recommend using a sparse matrix if the number of coordinates (length(points)) is much smaller (<10%) than n*m. This will make better use of memory and save you time.

points=[1,30,8;1,20,7];
grid = sparse(points(1,:), points(2,:), 1, n ,m);