[Numpy-discussion] assigning to submatrix

John Hunter jdhunter at ace.bsd.uchicago.edu
Tue Jul 29 09:33:02 CDT 2003


If I have a large matrix, say

  a = zeros( (20,20) )

and a small matrix

  b = ones( 3,4 )

and a list of row indices and a list of col indices

  rind = [2,4,9,15]
  cind = [1,4,12]

what is the best way to assign the submatrix to a[rind,cind].  I
understand this is possible in numarray, but is there a good way to do
it in Numeric?

In matlab, you could do a(rind, cind)=b;  Is there some reshape, put
magic I can do to make this efficient in Numeric?

Thanks,
John Hunter




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