[Numpy-discussion] Vectorizing array updates

Robert Kern robert.kern@gmail....
Wed Apr 29 16:58:21 CDT 2009


On Wed, Apr 29, 2009 at 16:19, Dan Goodman <dg.gmane@thesamovar.net> wrote:
> Robert Kern wrote:
>> On Wed, Apr 29, 2009 at 08:03, Daniel Yarlett <daniel.yarlett@gmail.com> wrote:
>>
>>> As you can see, Current is different in the two cases. Any ideas how I
>>> can recreate the behavior of the iterative process in a more numpy-
>>> friendly, vectorized (and hopefully quicker) way?
>>
>> Use bincount().
>
> Neat. Is there a memory efficient way of doing it if the indices are
> very large but there aren't many of them? e.g. if the indices were
> I=[10000, 20000] then bincount would create a gigantic array of 20000
> elements for just two addition operations!

indices -= indices.min()

-- 
Robert Kern

"I have come to believe that the whole world is an enigma, a harmless
enigma that is made terrible by our own mad attempt to interpret it as
though it had an underlying truth."
  -- Umberto Eco


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