How to create a "scatter" matrix without using a for loop?
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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]
采纳的回答
M = zeros(4);
row = [1,2,3];
col = [2,4,4];
val = [123,321,456];
ind = sub2ind(size(M),row,col)
M(ind) = val
更多回答（1 个）
row = [1,2,3];
col = [2,4,4];
val = [123,321,456];
M = accumarray([row.', col.'], val.', [4 4])
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