Replacing values in a matrix based on values in a column vector
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I have a column vector (with dimensions m x 1) which contains values from 1 to 10.
I want to make a matrix yMat with dimension m x 10, such that, in corresponding rows of y and yMat, the value at the column of yMat corresponding to the value in y is equal to 1.
All other values in yMat should be 0.
For example, if
y = [2; 4; 1; 8]
then
yMat = [0 1 0 0 0 0 0 0 0 0; 0 0 0 1 0 0 0 0 0 0; 1 0 0 0 0 0 0 0 0 0; 0 0 0 0 0 0 0 1 0 0]
The following code works, but is there any way to do this without using a for loop?
yMat = zeros(m, 10); % m is the number of rows in column vector y
for i = 1:m
yMat(i, y(i)) = 1;
end
Accepted Answer
More Answers (1)
Mara
on 21 Jun 2020
I came up with this. But not sure if this the easiest way to do it.
yMat = zeros(length(y)*10, 1);
yMat((y-1)*length(y)+ (1:length(y))') =1;
yMat = reshape(yMat, length(y), []);
2 Comments
Digaamber Dhamija
on 21 Jun 2020
Edited: Digaamber Dhamija
on 21 Jun 2020
Mara
on 21 Jun 2020
True, it does not have to be a vector for the indexing to work. Thanks for the feedback! I did not see that you received another answer already, it seems to be more intuitive than this one, anyways.
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