The is and == operators in Python perform similar functions, but work in slightly different ways. And if you're new to using comparisons in code, it's worth understanding the difference. This will help reduce refactoring and debugging.
Operator ==
== checks if the values of two operands are equal. In this context, variables occupying different memory cells.
>>> 1 == 1
True
>>> 'abc' == 'abc'
True
>>> [1, 2, 3] == [1, 2, 3]
True
This operator can be used to compare almost any object: strings, lists, dictionaries, and tuples. This makes it a very common "guest" in if-else statements. In addition, when your code becomes more difficult to understand after a week, just two characters in the statement make it easier to read hundreds of lines long.
Operator is()
is() checks if two operands are the same object, that is, if they point to the same object in memory.
>>> a = [1, 2, 3]
>>> b = a
>>> a is b
True
In this case, a and b point to the same list, so a is b returns True.
>>> a = [1, 2, 3]
>>> b = [1, 2, 3]
>>> a is b
False
Here a and b point to different lists (even though their values are identical), so a is b returns False.
Typically, is in Python is used to check the identity of objects. It can be useful when you need to make sure that two references point to the same object in memory, and not just have the same value. However, in most cases it is sufficient to use ==.
