[Numpy-discussion] Empty arrays strange behaviour

Nadav Horesh nadavh at visionsense.com
Wed Aug 18 04:51:18 CDT 2004



-----Original Message-----
From:	Todd Miller [mailto:jmiller at stsci.edu]
Sent:	Wed 18-Aug-04 13:46
To:	Nadav Horesh
Cc:	numpy-discussion
Subject:	Re: [Numpy-discussion] Empty arrays strange behaviour
On Wed, 2004-08-18 at 07:36, Nadav Horesh wrote:
> >>> a = arange(20, shape=(4,5))
> >>> a
> array([[ 0,  1,  2,  3,  4],
>        [ 5,  6,  7,  8,  9],
>        [10, 11, 12, 13, 14],
>        [15, 16, 17, 18, 19]])
> >>> a[2:4,5:7]   # Shouldn't it raise index error?
> array([])

I wasn't sure about this,  but what we're doing is faithful to what
Numeric does.

> >>> a[2:4, 5:7].iscontiguous()
> 0    # ????

Likewise here.

> >>> a[2:4, 5:7].copy().iscontiguous()
> 0    # ????

We're not compatible here.

> Shouldn't iscontiguous method of empty arrays and array.copy() return 1?

I'd say we should go with compatibility.

Todd



It isn't a major flaw, so compatibility is OK.
I got to this issue since I had a bug. If there was an option to get an IndexError exception it would ease the debugging.

Thank you,
  Nadav.




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