I can't remove a class object from a list

Question

So I have this list (Sheep is a class i created, requiring one parameter):

list = [Sheep(2), Sheep(3), Sheep(3), Sheep(4), Sheep(4), Sheep(4), Sheep(5), Sheep(5), Sheep(5), Sheep(5), Sheep(6), Sheep(6), Sheep(6), Sheep(7), Sheep(7), Sheep(8)]

However, when I try to remove Sheep(2) (list.remove(Sheep(2)) from the list, it returns ValueError: list.remove(x): x not in list

How do I fix this?

Answer 1

To test for membership in a python list with a custom class you must provide an equality (__eq__) method

class Sheep:

    def __init__(self, x):
        self.x = x

    def __eq__(self, other):
        assert isinstance(other, Sheep)
        return self.x == other.x

Now you can create instances of your class with the same "x" and they will be members of your list

foo = [Sheep(2), Sheep(3), Sheep(3), Sheep(4), Sheep(4), Sheep(4), Sheep(5), Sheep(5), Sheep(5), Sheep(5), Sheep(6), Sheep(6), Sheep(6), Sheep(7), Sheep(7), Sheep(8)]
print(Sheep(2) in foo)  # True

And you should be able to remove them too

foo.remove(Sheep(2))
print(foo)  # [Sheep(3), Sheep(3), Sheep(4), Sheep(4), Sheep(4), Sheep(5), Sheep(5), Sheep(5), Sheep(5), Sheep(6), Sheep(6), Sheep(6), Sheep(7), Sheep(7), Sheep(8)]

Answer 2

The two Sheep(2)s are different objects.

To let the the first Sheep(2) be found by comparing it to the second one, define equality on your Sheep. Then

class Sheep: 
    def __init__(self, camouflage_score): 
       self.camo = camouflage_score          

    def __eq__(self, other):
        return other and self.camo == other.camo