[Numpy-discussion] advanced indexing bug with huge arrays?

David Warde-Farley wardefar@iro.umontreal...
Mon Jan 23 14:33:53 CST 2012


On Mon, Jan 23, 2012 at 08:38:44PM +0100, Robin wrote:
> On Mon, Jan 23, 2012 at 7:55 PM, David Warde-Farley
> <wardefar@iro.umontreal.ca> wrote:
> > I've reproduced this (rather serious) bug myself and confirmed that it exists
> > in master, and as far back as 1.4.1.
> >
> > I'd really appreciate if someone could reproduce and confirm on another
> > machine, as so far all my testing has been on our single high-memory machine.
> 
> I see the same behaviour on a Winodows machine with numpy 1.6.1. But I
> don't think it is an indexing problem - rather something with the
> random number creation. a itself is already zeros for high indexes.
> 
> In [8]: b[1000000:1000010]
> Out[8]:
> array([3429029, 1251819, 4292918, 2249483,  757620, 3977130, 3455449,
>        2005054, 2565207, 3114930])
> 
> In [9]: a[b[1000000:1000010]]
> Out[9]:
> array([[0, 0, 0, ..., 0, 0, 0],
>        [0, 0, 0, ..., 0, 0, 0],
>        [0, 0, 0, ..., 0, 0, 0],
>        ...,
>        [0, 0, 0, ..., 0, 0, 0],
>        [0, 0, 0, ..., 0, 0, 0],
>        [0, 0, 0, ..., 0, 0, 0]], dtype=uint8)
> 
> In [41]: a[581350:,0].sum()
> Out[41]: 0

Hmm, this seems like a separate bug to mine. In mine, 'a' is indeed being
filled in -- the problem arises with c alone. 

So, another Windows-specific bug to add to the pile, perhaps? :(

David


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