Removing items from a list

Thomas Philips tkpmep at gmail.com
Fri Feb 10 21:04:34 CET 2012


In the past, when deleting items from a list, I looped through the
list in reverse to avoid accidentally deleting items I wanted to keep.
I tried something different today, and, to my surprise, was able to
delete items correctly, regardless of the direction in which I looped,
in both Python 3.2.2. and 2..1 -  does the remove() function somehow
allow the iteration to continue correctly even when items are removed
from the midde of the list?

>>> x = list(range(10))
>>> x
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> for i in x:
	if i % 2 == 0:
		x.remove(i)

>>> x
[1, 3, 5, 7, 9]
>>> for i in reversed(x):
	if i % 2 == 0:
		x.remove(i)

>>> x
[1, 3, 5, 7, 9]
>>> x = list(range(10))
>>> for i in reversed(x):
	if i % 2 == 0:
		x.remove(i)


>>> x
[1, 3, 5, 7, 9]

Sincerely

Thomas Philips



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