Vectorized implementation for using a vector as an index for matrices

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Redouane Mohamed El Ghali CHADOULI
回答： Stephen23 2019-12-3
Hello, I have a culumn vector V of m numbers from 1 to 10.
I would like to crate a m x 10 matrix A where in each line i, the V(i) th element is set to 1 and rest to 0.
here's an example of the code I'm trying to vectorize :
A = zeros(m,10);
for i=1:m
A(v(i))=1;
end

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Stephen23
Stephen23 2019-12-3
Use sub2ind like this:
>> m = 7;
>> V = randi([1,10],1,m)
V =
9 10 2 10 7 1 3
>> A = zeros(m,10);
>> A(sub2ind(size(A),1:m,V)) = 1
A =
0 0 0 0 0 0 0 0 1 0
0 0 0 0 0 0 0 0 0 1
0 1 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 1
0 0 0 0 0 0 1 0 0 0
1 0 0 0 0 0 0 0 0 0
0 0 1 0 0 0 0 0 0 0
>>

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