# Learn Special Methods by Building a Vector Space - Step 52

### 告诉我们发生了什么：

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

Your method should return a new instance of the current class only when the type of other is either int or float.

### 到目前为止你的代码

``````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})'

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 isinstance(other, (int, float)):
kwargs = {i: getattr(self, i) * other for i in vars(self)}
return self.__class__(**kwargs)
else:
return NotImplemented

# User Editable Region

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}')

``````

### 挑战信息：

Learn Special Methods by Building a Vector Space - Step 52

what is your problem, or error info ?

# Step 52

Vectors can be multiplied by a scalar, i.e. a number that multiplies each single component. The result of scalar multiplication is a vector with the same orientation as the original vector but a different magnitude.
Implement the scalar multiplication by checking if `other` is either an `int` or a `float`. If it is, return a new instance of the current class that has each component of the starting vector multiplied by `other`. This will be the vector resulting from the scalar multiplication.
Make sure the methods can be applied to compute the scalar multiplication of vectors with any number of dimensions.

I need to write the mul method. This is the error message: Your method should return a new instance of the current class only when the type of other is either int or float. I don’t understand where I went wrong.

it is my code

``````    def __mul__(self, other):
if type(other) in (int, float):
....
``````

use `type` , not `isinstance`