On Wed, 2017-11-29 at 12:00 -0500, numpy-discussion-requ...@python.org wrote: > Date: Wed, 29 Nov 2017 14:56:28 +0000 (UTC) > From: "ZHUO QL (KDr2)" <zhu...@yahoo.com> > To: Discussion of Numerical Python <numpy-discussion@python.org> > Subject: [Numpy-discussion] Is there a way that indexing a matrix of > data with a matrix of indices? > Message-ID: <360382279.3966234.1511967388...@mail.yahoo.com> > Content-Type: text/plain; charset="utf-8" > > Hi, all > suppose: > - D, is the data matrix, its shape is? M x N- I, is the indices > matrix, its shape is M x K,? K<=N > Is there a efficient way to get a Matrix R with the same shape of I > so that R[x,y] = D[x, I[x,y]] ? > A nested for-loop or list-comprehension is too slow for me.?? > Thanks.
I don't know if this will be substantially faster, but you can try the following: I += np.array(range(M))[:, np.newaxis] * N R = D.ravel()[I.ravel()].reshape((M, K)) Eric > ---- > ZHUO QL (KDr2) http://kdr2.com > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: <http://mail.python.org/pipermail/numpy- > discussion/attachments/20171129/baeaddc0/attachment-0001.html> _______________________________________________ NumPy-Discussion mailing list NumPy-Discussion@python.org https://mail.python.org/mailman/listinfo/numpy-discussion
