Sparse vector transpose is slow
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I'm performing the operation
X = [X; x']
in my MATLAB code. x is a very large and very sparse vector which is created as a column vector
x = sparse(nonZeroRows, 1, vals, vectorLength, 1);
The problem is that taking the transpose x' is VERY slow. Also, creating x' directly through
xT = sparse(1, nonZeroRows, vals, 1, vectorLength);
is also very slow.
How can I perform this operation efficiently?
1 Comment
Walter Roberson
on 8 Feb 2012
I am not surprised at it being slow; sparse vectors are organized by columns (I think it was), one header per column used, so when you transpose to a row it has to create headers for each of those rows.
I do not know what (if anything) can be done to improve the situation.
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