On Apr 21, 2:56 pm, candide <cand...@free.invalid> wrote:
> Is the del instruction able to remove _at the same_ time more than one
> element from a list ?
>
> For instance, this seems to be correct :
>
> >>> z=[45,12,96,33,66,'ccccc',20,99]
> >>> del z[2], z[6],z[0]
> >>> z
> [12, 33, 66, 'ccccc', 20]
> >>>
>
> However, the following doesn't work :
>
> >> z=[45,12,96,33,66,'ccccc',20,99]
> >>> del z[2], z[3],z[6]
> Traceback (most recent call last):
> File "<stdin>", line 1, in <module>
> IndexError: list assignment index out of range
> >>>
>
> Does it mean the instruction
>
> del z[2], z[3],z[6]
>
> to be equivalent to the successive calls
>
> del z[2]
> del z[3]
> del z[6]
That's part of the problem. Let's look at a better example.
>>> z = [0,1,2,3,4,5,6]
>>> del z[0],z[3],z[6]
Traceback (most recent call last):
File "<pyshell#1>", line 1, in <module>
del z[0],z[3],z[6]
IndexError: list assignment index out of range
>>> z
[1, 2, 3, 5, 6]
Yes, the error was caused by the list shrinking between calls,
so the 6 did not get deleted. But notice that 3 is still there
and 4 is missing.
If you must delete this way, do it bottom up so that the index
remains valid for the subsequent calls:
>>> z = [0,1,2,3,4,5,6]
>>> del z[6],z[3],z[0]
>>> z
[1, 2, 4, 5]
>
> ?
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