Why is list.remove only removing every second item?

Question

In my Python 2.7.2 IDLE interpreter:

>>> mylist = [1, 2, 3, 4, 5]
>>> for item in mylist:
        mylist.remove(item)

>>> mylist
[2,          


        

Answer 1

That's because you're modifying the list while iterating over it, iterate over a shallow copy instead:

>>> mylist = [1, 2, 3, 4, 5]
>>> for item in mylist[:]:      #use mylist[:] or list(mylist)
            mylist.remove(item)
...     
>>> mylist
[]