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Created on 2020-11-25 20:54 by misianne, last changed 2022-04-11 14:59 by admin. This issue is now closed.
| Messages (2) | |||
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| msg381862 - (view) | Author: misianne (misianne) | Date: 2020-11-25 20:54 | |
I have a problem with slice().indices(): x=[0,1,2,3,4,5,6,7,8,9]*10 x[-91:-101:-3] # == [9, 6, 3, 0] OK! x[slice(*slice(-91,-101,-3).indices(len(x)))] # == [] WRONG! This is correct: x[-91:-100:-3] # == [9, 6, 3] OK! x[slice(*slice(-91,-100,-3).indices(len(x)))] # == [9, 6, 3] OK! This is not: x[-91:-101:-3] # == [9, 6, 3, 0] OK! x[slice(*slice(-91,-101,-3).indices(len(x)))] # == [] WRONG! The problem is that slice(-91,-101,-3).indices(len(x)) returns: (9,-1,-3) which result in an empty list, while: (9,None,-3) gives the correct result. |
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| msg381864 - (view) | Author: Mark Dickinson (mark.dickinson) *  |
Date: 2020-11-25 21:10 | |
This is essentially a duplicate of #11842. In short, slice.indices is working as intended here. It's best to think of slice.indices as start, stop and step arguments that could be provided to the range built-in function to get the set of relevant indices. |
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| History | |||
|---|---|---|---|
| Date | User | Action | Args |
| 2022-04-11 14:59:38 | admin | set | github: 86633 |
| 2020-11-25 21:10:34 | mark.dickinson | set | status: open -> closed superseder: slice.indices with negative step and default stop nosy: + mark.dickinson messages: + msg381864 resolution: duplicate stage: resolved |
| 2020-11-25 20:54:21 | misianne | create | |