Faster and More Efficient `squareform()`
6 views (last 30 days)
Show older comments
I'm using squareform(pdist(mX)) fairly often.
The problem is squareform() is so slow it makes use of pdist2(mX, mX) faster.
This is basically what squareform() does in the case above:
function [ mY ] = MySquareForm( vX )
numElements = numel(vX);
numDist = (1 + sqrt(1 + (8 * numElements))) / 2;
mY = zeros(numDist, numDist, class(vX));
mY(tril(true(numDist, numDist), -1)) = vX;
mY = mY + mY.';
end
Basically, imagine you have a symmetric matrix mX then the vector vx above is it lower tringular matrix vectorized.
Something like:
mX = randn(100, 100);
mX = mX + mX.';
mL = tril(mX, -1);
vX = mL(mL ~= 0);
If the diagonal of is zerod then one could reproduce mX from vX using MySquareForm().
Any ideas how to do the same more efficiently and faster?
Answers (0)
See Also
Categories
Find more on Gaussian Process Regression in Help Center and File Exchange
Products
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!