Remove item in list

Question

For an assignment, I want to remove all undesirable items in a list. This is an example of code that should remove all 1's from a list; however, when I run it, it returns None. Why is this?

v=[1,2,1,3,1,4,5,55,1]

for i in v:
    if i==1:
        result=v.remove(1)
    else:
        continue
print (result)

Take a look at https://docs.python.org/3/tutorial/datastructures.html (`list.remove(x)`) (as @pylang secified). — CristiFati, Jan 28 '18 at 03:03
Dup of : https://stackoverflow.com/questions/1207406/remove-items-from-a-list-while-iterating. Dont know HTF did I miss it the 1st time... — CristiFati, Jan 28 '18 at 03:21

score 0 · Answer 1 · answered Jan 28 '18 at 03:02

list.remove() mutates the list in-place. The method itself returns None. Print v to see results.

From the docs:

You might have noticed that methods like insert, remove or sort that only modify the list have no return value printed – they return the default None. 1 This is a design principle for all mutable data structures in Python.

Nir Alfasi · Answer 2 · 2018-01-28T03:09:48.773

0

you can filter your list:

Python 2:

v = filter(lambda x: x != 1, v)

Python 3:

v = filter((1).__ne__, v)

The code snippet in the question is basically equivalent to:

while 1 in v: 
    v.remove(1)

edited Jan 28 '18 at 03:09

answered Jan 28 '18 at 03:03

Nir Alfasi

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Remove item in list

2 Answers2