There is this code:
a = [1, 2, 3, 4, 5]
a[2:4:-1] # returns []
a[4:2:-1] # returns [5, 4]
Why statement a[2:4:-1] returns an empty list altough the range is specified?
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Saullo G. P. Castro
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scdmb
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What specific non-empty output did you expect? – lvc May 26 '13 at 09:58
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@jamylak none of the answers to that question discuss this situation. A few talk about `a[::-1]` reversing a list, but only gives any examples like this one (where start and end are both given, and step is negative), and another gives the (AFAICT, misleading) 'using a negative step reverses the interpretation of `start` and `end`' (`a[4:2:-1]` contains the value at index 4 and not the one at index 2, as expected under non-reversed interpretation). – lvc May 26 '13 at 10:08
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@lvc however they give a very detailed explanation on slicing – jamylak May 26 '13 at 10:09
1 Answers
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If you attempt to use a[2:4:-1] you try to go backward from list index 2 to 4 which will obviously not work.
George
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