Python Vector Class no attribute error

In summary: This function allows you to use the + operator on two Vec3 objects, which will perform the addition operation on the corresponding components. For example, if you have two Vec3 objects named v1 and v2, you can add them together using v1 + v2.To call this function, you would use the following syntax:v1.__add__(v2)Alternatively, you can use the + operator directly as v1 + v2, which will call the __add__ function behind the scenes. So in summary, to call functions of the Vec3 class, you need to use the proper syntax and make sure the function exists within the class.
  • #1
clope023
992
131
Hello all, my issue is in calling the attributes of a 3d vector class in python, this is the class I was working with:

import math

class Vec3:
''' A three dimensional vector '''
def __init__(self, v_x=0, v_y=0, v_z=0):
self.set( v_x, v_y, v_z )
def set(self, v_x=0, v_y=0, v_z=0):
if isinstance(v_x, tuple) or isinstance(v_x, list):
self.x, self.y, self.z = v_x
else:
self.x = v_x
self.y = v_y
self.z = v_z
def __getitem__(self, index):
if index==0: return self.x
elif index==1: return self.y
elif index==2: return self.z
else: raise IndexError("index out of range for Vec3")
def __mul__(self, other):
'''Multiplication, supports types Vec3 and other
types that supports the * operator '''
if isinstance(other, Vec3):
return Vec3(self.x*other.x, self.y*other.y, self.z*other.z)
else: #Raise an exception if not a float or integer
return Vec3(self.x*other, self.y*other, self.z*other)
def __div__(self, other):
'''Division, supports types Vec3 and other
types that supports the / operator '''
if isinstance(other, Vec3):
return Vec3(self.x/other.x, self.y/other.y, self.z/other.z)
else: #Raise an exception if not a float or integer
return Vec3(self.x/other, self.y/other, self.z/other)
def __add__(self, other):
'''Addition, supports types Vec3 and other
types that supports the + operator '''
if isinstance(other, Vec3):
return Vec3( self.x + other.x, self.y + other.y, self.z + other.z )
else: #Raise an exception if not a float or integer
return Vec3(self.x + other, self.y + other, self.z + other)
def __sub__(self, other):
'''Subtraction, supports types Vec3 and other
types that supports the - operator '''
if isinstance(other, Vec3):
return Vec3(self.x - other.x, self.y - other.y, self.z - other.z)
else: #Raise an exception if not a float or integer
return Vec3(self.x - other, self.y - other, self.z - other )
def __abs__(self):
'''Absolute value: the abs() method '''
return Vec3( abs(self.x), abs(self.y), abs(self.z) )
def __neg__(self):
'''Negate this vector'''
return Vec3( -self.x, -self.y, -self.z )
def __str__(self):
return '<' + ','.join(
[str(val) for val in (self.x, self.y, self.z) ] ) + '>'
def __repr__(self):
return str(self) + ' instance at 0x' + str(hex(id(self))[2:].upper())
def length(self):
''' This vectors length'''
return math.sqrt( self.x**2 + self.y**2 + self.z**2 )
def length_squared(self):
''' Returns this vectors length squared
(saves a sqrt call, usefull for vector comparisons)'''
return self.x**2 + self.y**2 + self.z**2
def cross(self, other):
'''Return the cross product of this and another Vec3'''
return Vec3( self.y*other.z - other.y*self.z,
self.z*other.x - other.z*self.x,
self.x*other.y - self.y*other.x )
def dot(self, other):
'''Return the dot product of this and another Vec3'''
return self.x*other.x + self.y*other.y + self.z*other.z
def normalized(self):
'''Return this vector normalized'''
return self/self.length()
def normalize(self):
'''Normalize this Vec3'''
self /= self.length()

With this written as a script I imported it into IPython thusly:

from Vec3 import *

v = Vec3(3,4,5)

v.add(3)
---------------------------------------------------------------------------
AttributeError Traceback (most recent call last)
C:\Users\CHUCK\Documents\<ipython-input-7-4b1689e130e9> in <module>()
----> 1 v.add(3)

AttributeError: Vec3 instance has no attribute 'add'

As you can see from the code above, add is clearly an attribute of class Vec3.

So my question is how can I call the functions of my class without this error?

Am I calling the class correctly?

Any and all help is appreciated.
 
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  • #2
The Vec3 class does not have an add function - however, it has a function named __add__

Code:
def __add__(self, other):
'''Addition, supports types Vec3 and other 
types that supports the + operator ''' 
if isinstance(other, Vec3):
return Vec3( self.x + other.x, self.y + other.y, self.z + other.z )
else: #Raise an exception if not a float or integer
return Vec3(self.x + other, self.y + other, self.z + other)
 

Related to Python Vector Class no attribute error

1. What does "Python Vector Class no attribute error" mean?

This error means that the Python program is trying to access an attribute that does not exist within the Vector class.

2. Why am I getting a "no attribute error" when using the Vector class?

This error can occur if you are trying to access an attribute that is not defined within the Vector class. It could also happen if there is a typo in the attribute name.

3. How can I fix the "no attribute error" in my Python program?

To fix this error, you will need to check the code where the error is occurring and make sure that the attribute you are trying to access is correctly defined in the Vector class. You should also check for any typos in the attribute name.

4. Can a "no attribute error" occur for other classes in Python?

Yes, this error can occur for any class in Python. It is a common error that happens when trying to access an attribute that does not exist within a class.

5. Is there a way to prevent "no attribute errors" in my Python code?

Yes, you can prevent this error by making sure that all attributes you are trying to access are correctly defined in the class. You can also use the hasattr() function to check if an attribute exists before trying to access it.

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