List problem

[Reinhold Birkenfeld]

Alex Martelli wrote:
> User <1 at 2.3> wrote:
>    ...
>> >In general, removing elements from a list while you're iterating though
>> >the list is a bad idea.  Perhaps a better solution is a list
>> >comprehension:
>> 
>> Unless you're using a while loop and iterating in reverse, for
>> example:
>> 
>> a = [0,1,2,3,4]
>> pos_max = len(a) - 1  # Maximum iterable element
>> pos = pos_max         # Current element
>> while pos >= 0:
>>       if a[pos] == 2:
>>               a.remove(2)
>>               pos_max = pos_max - 1
>>       pos = pos - 1
> 
> Still a bad idea.
> 
>     a[:] = [x for x in a if x != 2]
       ^^^
What are these for?

Reinhold

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