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Re: So what's happening here?

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On Fri, 05 Jun 2015 13:11:13 +0000, Paul Appleby wrote:

> (I'd have thought that id(a[1]) and id(b[1]) would be the same if they
> were the same element via different "views", but the id's seem to change
> according to rules that I can't fathom.)

First, a[1] and b[1] aren't views, they're scalars.

Second, different views on the same data are different objects, they just
share the same underlying data. Consider the case where the slice doesn't
cover the entire range:

> a = np.array([1,2,3])
> b = a[:2]
> a
array([1, 2, 3])
> b
array([1, 2])
> id(a)
139682716078288
> id(b)
139682716078368
> b[0] = 99
> a
array([99,  2,  3])
> b
array([99,  2])

The case where a slice *does* cover the entire range isn't special; the
resulting view is still a different object.

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Thread

So what's happening here? Paul Appleby <pap@nowhere.invalid> - 2015-06-05 12:46 +0000
  Re: So what's happening here? Fabien <fabien.maussion@gmail.com> - 2015-06-05 14:52 +0200
  Re: So what's happening here? Larry Martell <larry.martell@gmail.com> - 2015-06-05 08:55 -0400
  Re: So what's happening here? Peter Otten <__peter__@web.de> - 2015-06-05 15:09 +0200
  Re: So what's happening here? Paul Appleby <pap@nowhere.invalid> - 2015-06-05 13:11 +0000
    Re: So what's happening here? Gary Herron <gary.herron@islandtraining.com> - 2015-06-05 06:23 -0700
    Re: So what's happening here? Steven D'Aprano <steve@pearwood.info> - 2015-06-05 23:51 +1000
    Re: So what's happening here? Nobody <nobody@nowhere.invalid> - 2015-06-05 15:13 +0100

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