How to implement list subtraction?

by

Use a list comprehension:

[item for item in x if item not in y]

If you want to use the - infix syntax, you can just do:

class MyList(list):
    def __init__(self, *args):
        super(MyList, self).__init__(args)

    def __sub__(self, other):
        return self.__class__(*[item for item in self if item not in other])

you can then use it like: 

x = MyList(1, 2, 3, 4)
y = MyList(2, 5, 2)
z = x - y

But if you don’t absolutely need list properties (for example, ordering), just use sets as the other answers recommend.

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