[Numpy-discussion] array slicing questions

eat e.antero.tammi@gmail....
Tue Jul 31 10:57:31 CDT 2012


On Tue, Jul 31, 2012 at 6:43 PM, Nathaniel Smith <njs@pobox.com> wrote:

> On Tue, Jul 31, 2012 at 2:23 PM, eat <e.antero.tammi@gmail.com> wrote:
> > Apparently ast(.) does not return a view of the original matches rather a
> > copy of size (n* (2* distance+ 1)), thus you may run out of memory.
> The problem isn't memory, it's that on 32-bit Python,
> np.prod(arr.shape) must be <2**32 (or maybe 2**31 -- something like
> that).

I think this is what the traceback is indicating.

> Normally you wouldn't be creating such arrays anyway because
> they would be too big to fit into memory, so this problem isn't
> observed, but when you're using stride_tricks then it's very easy to
> create arrays that use only a small amount of memory but that have
> very large shapes.

But in this specific case .nbytes attribute indicates that a huge amount of
memory is used. So I guess stride_tricks(.) is not returning a view.

> Solution: don't buy more memory, just use a 64-bit
> Python, where the limit is 2**64 (or 2**63 or whatever).

> -n
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