Hi! I have a large M x K, M, K ~ 1e3 array L of indices - non-negative integers in the range 0 to N-1 - and an N x 3 array C (a matplotlib colormap). I need to create an M x K x 3 array R such that R[m,k,j] = C[L[m,k], j], j = 0,1,2. I want to do so w/out having to loop through all the (m,k) index pairs, but I'm having trouble wrapping my brain around how to do it - please help. Thanks. DG
I am pretty sure you should be able to do R = C[L, :] and get the array you want. Try it with a small matrix where you know the result you want. You may need to transpose some axes afterwards, but I don't think you should. On Tue, Jul 27, 2010 at 9:10 AM, David Goldsmith <d.l.goldsmith@gmail.com>wrote:
Hi! I have a large M x K, M, K ~ 1e3 array L of indices - non-negative integers in the range 0 to N-1 - and an N x 3 array C (a matplotlib colormap). I need to create an M x K x 3 array R such that R[m,k,j] = C[L[m,k], j], j = 0,1,2. I want to do so w/out having to loop through all the (m,k) index pairs, but I'm having trouble wrapping my brain around how to do it - please help. Thanks.
DG
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On Tue, Jul 27, 2010 at 9:32 AM, John Salvatier <jsalvati@u.washington.edu>wrote:
I am pretty sure you should be able to do
R = C[L, :] and get the array you want.
Try it with a small matrix where you know the result you want. You may need to transpose some axes afterwards, but I don't think you should.
Thanks, John, that works; you may be right about the transposing, but I can work that out empirically. Thanks again! DG
On Tue, Jul 27, 2010 at 9:10 AM, David Goldsmith <d.l.goldsmith@gmail.com>wrote:
Hi! I have a large M x K, M, K ~ 1e3 array L of indices - non-negative integers in the range 0 to N-1 - and an N x 3 array C (a matplotlib colormap). I need to create an M x K x 3 array R such that R[m,k,j] = C[L[m,k], j], j = 0,1,2. I want to do so w/out having to loop through all the (m,k) index pairs, but I'm having trouble wrapping my brain around how to do it - please help. Thanks.
DG
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-- Mathematician: noun, someone who disavows certainty when their uncertainty set is non-empty, even if that set has measure zero. Hope: noun, that delusive spirit which escaped Pandora's jar and, with her lies, prevents mankind from committing a general suicide. (As interpreted by Robert Graves)
participants (2)
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David Goldsmith -
John Salvatier