Suggestion: PEP for popping slices from lists
Peter Otten
__peter__ at web.de
Thu Aug 8 06:07:16 EDT 2013
Neatu Ovidiu Gabriel wrote:
> The list.pop(index) returns the element represented by the index and also
> reduces the list by removing that element. So it a short one liner for
> doing both things. But when it comes for popping a slice of the list there
> is nothing similar for doing in that simple way.
>
> If you want to remove a slice and also reduce the list you will have
> something like this:
>
> a_list, a_slice = a_list[:size], a_list[size:]
>
> or even worser if you try to do the same for something in the middle.
>
> My proposal is the extension of list.pop for accepting a way for popping
> slices.
>
> When doing this:
>
> a_list.pop(i,j)
>
> pop will return the slice [i,j] and remove it from the list.
>
> For popping from an index to the end:
>
> a_list.pop(i, len(a_list))
>
> Or even emptying the whole list:
>
> a_list.pop(0, len(a_list))
>
>
> So this is it :)
You'd use 'del' to remove a slice from a list. So:
>>> def pop_slice(items, *indices):
... x = slice(*indices)
... result = items[x]
... del items[x]
... return result
...
>>> items = range(10)
>>> pop_slice(items, 3)
[0, 1, 2]
>>> items
[3, 4, 5, 6, 7, 8, 9]
>>> pop_slice(items, 3, 4)
[6]
>>> items
[3, 4, 5, 7, 8, 9]
>>> pop_slice(items, None, None, 2)
[3, 5, 8]
>>> items
[4, 7, 9]
But what's your use case?
Does it occur often enough that you cannot afford a two-liner like
result = items[start:stop]
del items[start:stop]
?
More information about the Python-list
mailing list