[Numpy-discussion] Would a patch with a function for incrementing an array with advanced indexing be accepted?

John Salvatier jsalvati@u.washington....
Tue Jun 26 11:46:46 CDT 2012


Hello,

If you increment an array using advanced indexing and have repeated
indexes, the array doesn't get repeatedly incremented,
http://comments.gmane.org/gmane.comp.python.numeric.general/50291. I wrote
a C function that does incrementing with repeated indexes correctly. The
branch is here (https://github.com/jsalvatier/numpy see the last two
commits). Would a patch with a cleaned up version of a function like this
be accepted into numpy? I'm not experienced writing numpy C code so I'm
sure it still needs improvement.

If you compile and install that branch, you can test the code using:

from numpy import *
from numpy.core.multiarray import index_increment

a = arange(12).reshape((3,4))
index = ([1,1,2,0], [0,0,2,3])
vals = [50,50., 30.,16]

b = index_increment(a, index, vals)

print b

"""
should print out:
 [[   0.    1.    2.   19.]
 [ 104.    5.    6.    7.]
 [   8.    9.   40.   11.]]
"""

Cheers,
John
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