On Mon, 21 Nov 2005 02:49:56 -0800, Shi Mu wrote:
> I used the following method to remove duplicate items in a list and
> got confused by the error.
>
>>>> a
> [[1, 2], [1, 2], [2, 3]]
>>>> noDups=[ u for u in a if u not in locals()['_[1]'] ]
> Traceback (most recent call last):
> File "<interactive input>", line 1, in ?
> TypeError: iterable argument required
Confused by the error? I'm confused by your code!!!
If you want to remove duplicate items in a list, try something like this:
def remove_dups(L):
"""Removes duplicate items from list L in place."""
# Work backwards from the end of the list.
for i in range(len(L)-1, -1, -1):
# Check to see if the current item exists elsewhere in
# the list, and if it does, delete it.
if L[i] in L[:i]:
del L[i]
Instead of deleting duplicate items in place, we can create a new list
containing just the unique items:
def unique_items(L):
"""Returns a new list containing the unique items from L."""
U = []
for item in L:
if item not in U:
U.append(item)
return U
The trick you are trying to do with _ is undocumented and, even if you get
it to work *now*, is probably not going to work in the future. Don't do it.
--
Steven.
--
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