I have the following code, which sortings_list consist of 2 items like
sortings_list = ['code', 'name']
for i in xrange(0, len(sortings_list)):
if sortings_list[i] == '-%s' % field:
sortings_list.pop(i)
Any ideas ?
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3 Answers
You are removing items from a list while iterating, if you remove the first item then the second item's index changes. Use a list comprehension instead:
sortings_list = [elem for elem in sortings_list if not elem == '-%s' % field]
answered May 1, 2013 at 21:23
Martijn Pieters
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Comments
You're calling pop() on the first item which removes it, and now the list only has one element.
Then you try to iterate to the second item, which doesn't exist anymore.
Comments
You are better off using list comprehension because indexing is messy. With Python, you don't need to index a list in most cases. That being said, if you still insist on using your solution:
for i in xrange(len(sortings_list) - 1, -1, -1):
if ...:
sortings_list.pop(i)
That is, you start from the end of the list and traverse backward. That way, all the indexing still works. Again, I highly recommend against doing things this way. Go with list comprehension which Martijn Pieters offers.
