[Numpy-discussion] Initial implementation of histogram_discrete()
David Warde-Farley
dwf@cs.toronto....
Sun Nov 15 01:16:44 CST 2009
On 14-Nov-09, at 10:57 AM, Bruce Southey wrote:
> Is it just that bincount does not count negative numbers?
> If so, then I would strongly argue that is insufficient for creating
> new function. Rather you need to provide a suitable patch to fix
> bincount or replace bincount with a better version.
The whole point of bincount is that in the result array, the indices
correspond to _values_ in the original array, i.e. bc = bincount(arr)
then bc[3] gives me the number of 3's that appear in arr. This is lost
if bincount starts reporting negatives. I suppose you could return a
tuple of two arrays, optionally, but I don't know how much use it
would get.
If you really need to do bincount on an array with negative ints, you
can just add -arr.min() to the array first and subtract the same value
when done. Assuming you don't have a huge array this will be very
fast, and can even be done in place.
David
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