[Numpy-discussion] Sparse matrices
Victor S. Miller
victor at idaccr.org
Tue Jul 30 08:29:06 CDT 2002
Sorry, I had a typo in the program. It should be:
# M is n by k, and represents a sparse n by n matrix A
# the non-zero entries of row i of A start in column loc[i]
# and are the i-th row of M in locations loc[i]:loc[i]+k
# loc is the location vector
n,k = M.shape
mm = reshape(v,(-1,1))*M
w = zeros((n+m),v.typecode())
# is there a trick to replace the loop below?
for i in range(mm.shape[0]):
w[loc[i]:loc[i]+k] += mm[i]
w = w[:n]
--
Victor S. Miller | " ... Meanwhile, those of us who can compute can hardly
victor at idaccr.org | be expected to keep writing papers saying 'I can do the
CCR, Princeton, NJ | following useless calculation in 2 seconds', and indeed
08540 USA | what editor would publish them?" -- Oliver Atkin
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