On Sun, Oct 28, 2012 at 9:12 PM, <andrewr3m...@gmail.com> wrote:
> The slice operator does not give any way (I can find!) to take slices from
> negative to positive indexes, although the range is not empty, nor the
> expected indexes out of range that I am supplying.
>
> Many programs that I write would require introducing variables and logical
> statements to correct the problem which is very lengthy and error prone
> unless there is a simple work around.
>
> I *hate* replicating code every time I need to do this!
>
> I also don't understand why slice() is not equivalent to an iterator, but can
> replace an integer in __getitem__() whereas xrange() can't.
>
>
> Here's an example for Linux shell, otherwise remove /bin/env...
> {{{#!/bin/env python
> a=[1,2,3,4,5,6,7,8,9,10]
> print a[-4:3] # I am interested in getting [7,8,9,10,1,2] but I get [].
> }}}
For a sequence of length 10, "a[-4:3]" is equivalent to "a[6:3]",
which is an empty slice since index 6 is after index 3.
If you want it to wrap around, then take two slices and concatenate
them with "a[-4:] + a[:3]".
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