How to create a "scatter" matrix without using a for loop?

I am trying to create a matrix given size, x-coordinate, y-coordinate, and value. Ideally, I would like to avoid using a for loop as I usually work with large data sets.

For example, I have a 4x4 zero matrix.

M = zeros(4)
row = [1,2,3];
col = [2,4,4];
val = [123,321,456];

Is there a function or fast method turn this into:

M = [0 123 0  0;
     0  0  0 321;
     0  0  0 456;
     0  0  0  0]

Answer 1

[Cris LaPierre]

i think sub2ind will do the trick.

M = zeros(4);
row = [1,2,3];
col = [2,4,4];
val = [123,321,456];

ind = sub2ind(size(M),row,col)

ind = 1×3

5 14 15

M(ind) = val

M = 4×4

0 123 0 0 0 0 0 321 0 0 0 456 0 0 0 0

Answer 2

[Steven Lord]

row = [1,2,3];
col = [2,4,4];
val = [123,321,456];
M = accumarray([row.', col.'], val.', [4 4])

M = 4×4

0 123 0 0 0 0 0 321 0 0 0 456 0 0 0 0