Membership operators in Python allow us to check if a value is present within a sequence (such as a string, list, tuple, or set).
| Operator | Name | Description |
|---|---|---|
in | In | Returns True if the value is found in the sequence |
not in | Not in | Returns True if the value is not found in the sequence |
List of membership operators
in Operator
The in operator is used to check if a value is present in a sequence.
fruits = ["apple", "banana", "cherry"]
is_banana = "banana" in fruits # True
is_grape = "grape" in fruits # False
In this example, we are checking if "banana" is present in the fruits list, which is True. We also check if "grape" is present, which is False.
not in Operator
The not in operator is used to check if a value is NOT present in a sequence.
fruits = ["apple", "banana", "cherry"]
is_not_grape = "grape" not in fruits # True
is_not_apple = "apple" not in fruits # False
In this example, we are checking if "grape" is NOT present in the fruits list, which is True. We also check if "apple" is NOT present, which is False.
Usage examples
Checking elements in a list
colors = ["red", "green", "blue"]
is_blue = "blue" in colors # True
is_not_yellow = "yellow" not in colors # True
Checking characters in a string
name = "Luis"
has_a = "a" in name # True
does_not_have_z = "z" not in name # True
Checking elements in a set
vowels = {"a", "e", "i", "o", "u"}
is_a_vowel = "a" in vowels # True
is_not_y = "y" not in vowels # True