Remove all occurences of a value from a Python list

Question

In Python remove() will remove the first occurrence of value in a list.

How to remove all occurrences of a value from a list, without sorting the list?

This is what I have in mind.

>>> x = [1, 2, 3, 4, 2, 2, 3]
>>> def remove_values_from_list(the_list, val):
        while val in the_list:
            the_list.remove(val)

>>> remove_values_from_list(x, 2)
>>> 
>>> x
[1, 3, 4, 3]

Answer 1

You can use a list comprehension:

def remove_values_from_list(the_list, val):
   return [value for value in the_list if value != val]

x = [1, 2, 3, 4, 2, 2, 3]
x = remove_values_from_list(x, 2)
print x
# [1, 3, 4, 3]

Answer 2

Functional approach:

>>> x = [1,2,3,2,2,2,3,4]
>>> filter (lambda a: a != 2, x)
[1, 3, 3, 4]

Answer 3

You can use slice assignment if the original list must be modified, while still using an efficient list comprehension (or generator expression).

>>> x = [1, 2, 3, 4, 2, 2, 3]
>>> x[:] = (value for value in x if value != 2)
>>> x
[1, 3, 4, 3]