# Learn Special Methods by Building a Vector Space - Step 66

### Tell us what’s happening:

i don’t know how this is wrong? am i not comparing the norms here??

### 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})'

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)

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 type(self) == type(other):
args = [getattr(self, i) * getattr(other, i) for i in vars(self)]
return sum(args)
return NotImplemented

def __eq__(self, other):
if type(self) != type(other):
return NotImplemented
return all(getattr(self, i) == getattr(other, i) for i in vars(self))

def __ne__(self, other):
return not self == other

# User Editable Region

def __lt__(self, other):
if type(self) != type(other):
return NotImplemented
return norm(self,i) < norm(other,i)

# 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}')
v5 = v1 * v2
print(f'v1 * v2 = {v5}')
print(v1 != R2Vector(x=2, y=3))

``````

### Your browser information:

User Agent is: `Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/126.0.0.0 Safari/537.36`

### Challenge Information:

Learn Special Methods by Building a Vector Space - Step 66

i’ve not got this `def __lt__(self, other): if type(self) != type(other): return NotImplemented return self.norm > self.other `

ive fixed the less that sign

`norm` is a method, and you should call it properly.

`<object>.norm()` where `<object>` is either `self` or `other` in this case.

1 Like

Test it by making 2 R3Vector objects and printing a less than comparison.

``````v1 = R3Vector(x=2, y=3, z=3)
v2 = R3Vector(x=0.5, y=1.25, z=3)
print(v1 < v2 )
``````

Then see if an error is generated.