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Python Python Collections (2016, retired 2019) Lists Removing Items From A List

Posted by Eswar Ambati
Eswar Ambati
890 Points

Don't understand what remove function actually does?

I the video an example of a list was used:

my_list = [1, 2 , 3, 1] my_list.remove(1)

Why does this not remove all numbers with the value of 1 immediately.... But just removes the first value of 1 in the list. I didn't really understand his explanation

1 Answer

Kyle Knapp
Kyle Knapp
21,526 Points
Kyle Knapp
Kyle Knapp
21,526 Points

.remove() only removes the first item it finds in the list.

>>> arr = [1,2,3,1]
>>> arr.remove(1)
>>> arr
[2, 3, 1]

If you want to remove all 1's you can use filter.

>>> arr = [1,2,3,1]
>>> list(filter(lambda x: x != 1, arr))
>>> arr
[2, 3]

You could also use a while loop, but I don't recommend it.

>>> while 1 in arr:
      arr.remove(1)
>>> arr
[2, 3]
Eswar Ambati
Eswar Ambati
890 Points

However the person does my_list.remove(1) again but this time it deleted the last item instead of deleting the second item.