Question

In Python, is there a way to check for duplicate items in a list, and if there is, then remove them? I’m looking for something like this:

>>> def check():
>>>    # put code here
>>> list = ["foo", "foo", "bar"]
>>> check(list)
>>> list
["foo", "bar"]
>>> list2 = ["foo", "bar", "example"]
>>> check(list2)
>>> list2
["foo", "bar", "example"]

Thanks in advance!

Update:

Guys, I’m really new at programming, and the order doesn’t really matter. So a for loop should be fine. But thanks anyways!

Answer 1

A set might be a better data structure here, as it can’t have duplicates in the first place. You can also use it as a tool to uniquify your list:

>>> lst = ["bar", "foo", "foo"]
>>> set(lst)
set(['foo', 'bar'])
>>> list(set(lst))
['foo', 'bar']

Or if you need to preserve the order, you can keep your data in an OrderedDict:

>>> from collections import OrderedDict
>>> d = OrderedDict.fromkeys(lst)
>>> d
OrderedDict([('bar', None), ('foo', None)])
>>> list(d)
['bar', 'foo']

Note that for performance reasons it would be more ideal to use the right data structure in the first place, rather than using a raw list and removing duplicates from it after every operation using one of these transformations.