How to compare two instances of an object Python?

Attempting to compare two objects data members; however, the error message has no specific details, which leaves me with little information on how to go about correcting it

class Person:
def __init__(self, name, age, id):
self.name = name
self.age = age
self.id = id

def same_person(Person lhs, Person rhs):
return lhs.id == rhs.id

person1 = Person("David Joyner", 30, 901234567)
person2 = Person("D. Joyner", 29, 901234567)
person3 = Person("David Joyner", 30, 903987654)
# print calls provided as part of an exercise: not my implementation
print(same_person(person1, person2))
print(same_person(person1, person3))


4 Answers
4

The other answers are correct and provide the best way to do it, but I realized that you wrote:

print calls provided as part of an exercise: not my implementation

print(same_person(person1, person2))
print(same_person(person1, person3))


The exercise probably wants you to define a function outside the class. You can do that by removing that function from the class and writing it un-indented outside the class (without providing class type too). For example:

class Person:
def __init__(self, name, age, id):
self.name = name
self.age = age
self.id = id

def same_person(lhs, rhs):
return lhs.id == rhs.id

person1 = Person("David Joyner", 30, 901234567)
person2 = Person("D. Joyner", 29, 901234567)
person3 = Person("David Joyner", 30, 903987654)

print(same_person(person1, person2))
print(same_person(person1, person3))


__eq__()

same_person is a method of the class Person and should take just an argument as input. It should be defined as:

Person

def same_person(self, other):
return self.id == other.id


and called as

person1.same_person(person2)


or you could override the __eq__ method (i.e., ==).

__eq__

==

def __eq__(self, other):
return self.id == other.id


in order to be able to do it as person1 == person2

person1 == person2

return self is other

Person(1, 2, 3) != Person(1, 2, 3)

self.id is other.id

self.id == other.id

self is other

class Person:
def __init__(self, name, age, id):
self.name = name
self.age = age
self.id = id

def same_person(self, lhs, rhs):
return lhs.id == rhs.id


you dont have to define lhs and rhs type in python unless you are using typings.

Quite a few mistakes:

Person

person1

person2

person3

same_person

This is what I would do:

class Person:
def __init__(self, name, age, id):
self.name = name
self.age = age
self.id = id

def same_person(self, other):
return self.id == other.id

person1 = Person("Bob", 25, 1)
person2 = Person("Mike", 33, 1)
person3 = Person("Maria", 28, 2)

print(person1.same_person(person2))
print(person1.same_person(person3))


Output:

True
False


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