On Mon, May 19, 2008 at 9:34 AM, Orest Kozyar <

[hidden email]> wrote:

> Given a slice, such as s_[..., :-2:], is it possible to take the

> complement of this slice? Specifically, s_[..., ::-2].

Hmm, that doesn't look like the complement. Did you mean s_[..., -2:]

and s_[..., :-2]?

> I have a

> series of 2D arrays that I need to split into two subarrays via

> slicing where the members of the second array are all the members

> leftover from the slice. The problem is that the slice itself will

> vary, and could be anything such as s_[..., 1:4:] or s_[..., 1:-4:],

> etc, so I'm wondering if there's a straightforward idiom or routine in

> Numpy that would facilitate taking the complement of a slice? I've

> looked around the docs, and have not had much luck.

In general, for any given slice, there may not be a slice giving the

complement. For example, the complement of arange(6)[1:4] should be

array([0,4,5]), but there is no slice which can make that. Things get

even more difficult with start:stop:step slices let alone simultaneous

multidimensional slices. Can you be more specific as to exactly the

variety of slices you need to support?

--

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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