zip as iterator and bad/good practices
Terry Reedy
tjreedy at udel.edu
Fri Jun 12 19:43:08 EDT 2015
On 6/12/2015 4:34 PM, Laura Creighton wrote:
> The real problem is removing things from lists when you are iterating
> over them, not adding things to the end of lists.
One needs to iterate backwards.
>>> ints = [0, 1, 2, 2, 1, 4, 6, 5, 5]
>>> for i in range(len(ints)-1, -1, -1):
if ints[i] % 2:
del ints[i]
>>> ints
[0, 2, 2, 4, 6]
But using a list comp and, if necessary, copying the result back into
the original list is much easier.
>>> ints = [0, 1, 2, 2, 1, 4, 6, 5, 5]
>>> ints[:] = [i for i in ints if not i % 2]
>>> ints
[0, 2, 2, 4, 6]
--
Terry Jan Reedy
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