[Numpy-discussion] vectorizing histogram-like computation

[Piotr L. <lus...@cs...>]

All,

I apologize if this is a dupe. I haven't seen it where I looked.

There is numarray.numeric.histogram and numarray.mlab.histogram.
What they do is this (more or less):

for idx in arr:
    histogram[idx] += 1

What I want to do is:

for idx in arr:
    result[idx] ^= value

Doing:

result[arr] ^= value

doesn't work. Which is not surprising because:

histogram[arr] += 1

doesn't work either.

My question is whether there is a way to do it (the XOR example)
without using a for loop.

Thanks,

Piotr