Learn Special Methods by Building a Vector Space - Step 53

Python
1

Tell us what’s happening:

My code doesn’t pass. I’m not sure if I am using the correct methods. The instructions are quite hard to understand.

Your code so far

class R2Vector:
    def __init__(self, *, x, y):
        self.x = x
        self.y = y

    def norm(self):
        return sum(val**2 for val in vars(self).values())**0.5

    def __str__(self):
        return str(tuple(getattr(self, i) for i in vars(self)))

    def __repr__(self):
        arg_list = [f'{key}={val}' for key, val in vars(self).items()]
        args = ', '.join(arg_list)
        return f'{self.__class__.__name__}({args})'

    def __add__(self, other):
        if type(self) != type(other):
            return NotImplemented
        kwargs = {i: getattr(self, i) + getattr(other, i) for i in vars(self)}
        return self.__class__(**kwargs)

    def __sub__(self, other):
        if type(self) != type(other):
            return NotImplemented
        kwargs = {i: getattr(self, i) - getattr(other, i) for i in vars(self)}
        return self.__class__(**kwargs)

# User Editable Region

    def __mul__(self, other):
        if type(other) in (int, float):
            kwargs = {i: getattr(self, i) * other for i in vars(self)}
            return self.__class__(**kwargs)
        elif isinstance(other, self.__class__):
            pass

# User Editable Region

        elif isinstance(type(other), self.__class__):
            pass
class R3Vector(R2Vector):
    def __init__(self, *, x, y, z):
        super().__init__(x=x, y=y)
        self.z = z

v1 = R2Vector(x=2, y=3)
v2 = R2Vector(x=0.5, y=1.25)
print(f'v1 = {v1}')
print(f'v2 = {v2}')
v3 = v1 + v2
print(f'v1 + v2 = {v3}')
v4 = v1 - v2
print(f'v1 - v2 = {v4}')

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Challenge Information:

Learn Special Methods by Building a Vector Space - Step 53

2

You seem to have some extra code in there, but the first elif seems correct to me, although it also does not pass for me.

3

I got it, use the same method that you use in the def __add__(self, other): method:

def __add__(self, other):
        if type(self) != type(other):
            return NotImplemented
        kwargs = {i: getattr(self, i) + getattr(other, i) for i in vars(self)}
        return self.__class__(**kwargs)
2 Likes
4

I don’t seem to understand. What do I add for the code to pass?

1 Like
5

Hi @cjstaz13!

The instructions is looking for you to compare your two parameters of __mul__ to see if they are the same Class/type.

As @pkdvalis is pointing out, you did this with __sub__ and __add__ before. However, you were comparing to see if they were not equal (!=) to the same Class/type.

Look back at your code. You’ve done this before. You’re just putting it in an elif now, and using the is equal to operator (==).

For the code inside the elif, use pass. It looks like you add more in the next step.

I hope this helps. Happy Coding!

2 Likes
6

Use type(), not isinstance()

I think both are correct but the tests require type()