NOT IN operator in Python

This page contains all the information about “not in” operator in python. You can also know everything about what type of operator is “not in” in python language and where it is used.

Membership Operators in Python

There are only two membership operators in python. One of the two membership operators is the “not in” operator. The membership operators in python language are used to check if a given element, i.e., either a value or a variable is present in an iterator or not. So, when we want to check if a value or a value stored in a variable is present or not, then a membership operator is used to determine it.

What is NOT IN operator

A not-in operator is one of the two membership operators, as said above. It is used to validate if an element is present or not in an iterator. The not-in operator is written with a " not in " keyword in Infront of the iterator. In this way, a statement containing the " not in " operator returns if the operator is present in the iterator or not.

Syntax of NOT IN operator

Element not in declared_iterator

Here, first, the element name is given, which we want to validate its presence. Following the element, the " not in " keyword is used to implement the " not in " membership operator. At last, the name of the iterator is given, which may or may not contain the element in it we want to validate.

The return type of NOT IN operator

When a membership operator like the “not in” operator is used, the value that is returned is a “Boolean”. This means that if the given element is present in the iterator, then the statement returns the value " FALSE ", and if the element is not present in the iterator, then the statement returns the value " TRUE “. So, the output for a statement containing a “not in” membership operator is either “TRUE” or “FALSE”.

Where is NOT IN operator used?

The “not in” membership operator can be used on different iterators present in Python, such as:

1. A list.
2. A tuple.
3. A set.
4. A dictionary.
5. Range function.
6. An array.
7. A string.

Using NOT IN on a List

The “not in" operator can be used in a statement containing a list as an iterator. The values are stored in a list, and the list is declared. Then a statement containing the " not in " operator is used, and the output will return a Boolean value.

Example of NOT IN operator used in list

# the declaration of a list in python.
list = [10, 20, 30, 40, 50]


# statement using the " not in " operator.
print(10 not in list)


# Output will return " False " as the list consists of the 
# number 10.

Output

Here, as we can see, a list is declared with five elements in it. Then a statement is written with " not in " operator and the list. The output is " False " as the element “10” is present in the list. The statement written says that “10” does not belong to the list, but “10” actually belongs to the declared list iterator.

Using NOT IN on a Tuple

The “not in” operator can be used in a statement which is containing a tuple as an iterator. Firstly, the values are stored in a tuple, and the tuple is declared. Then a statement containing the " not in " operator is used, and the output will return a Boolean value.

Example of NOT IN on a Tuple

# the declaration of a tuple in python.
Tup = ( 10, 20, 30, 40, 50 )


# statement using the " not in " operator.
print(5 not in Tup)


# Output will return " True " as the number 5 is not listed out # within the tuple “ Tup ”.

Output

Here, we can see a tuple “Tup” that is declared with five elements in it. Then a statement is written with “not in” operator and the tuple. The output is “True” as the element “5” is not present in the tuple. The statement written says that the number “5” does not belong to the tuple, so the output returns the Boolean value “True”. If at all the number “5” is listed within the tuple and then the same statement is given, the output will return “False”.

Using NOT IN on a Set

The “not in " operator can be used in a statement containing a set as an iterator. Firstly, the values are stored in a set, and then the set is declared. Then a statement containing the “not in” operator is used in the program, and then the output will return a Boolean value.

Example of NOT IN on a Set

# the declaration of a set in python.
anyset = { 10, 20, 30, 40, 50 }


# statement using the " not in " operator.
print(15 not in anyset)


# Output will return " True " as the number “ 15 ” is not 
# mentioned within the set “ anyset ”.

Output

Here, as we can see, a set is declared with five elements in it. Then a statement is written with “not in” operator and the set. The output returns to the Boolean value “True " as the element " 15 " is not present in the tuple. The statement written says that " 15 " does not belong to the tuple, so the output will return the Boolean value “True” as the given statement using “not in” is correct.

Using NOT IN on a Dictionary

The “not in” operator can be used in a statement containing a dictionary as an iterator. Firstly, the values are stored in a dictionary, and the dictionary is declared. Then a statement containing the " not in " operator is used, and the output will return a Boolean value. The dictionary always checks the keys” of its elements to find if the element is present or not in it.

Example of NOT IN on a Dictionary

# the declaration of a dictionary in python.
dict = { “a”: 10, “b”: 20, “c”: 30 }


# statement using the " not in " operator.
print(“a” not in dict)


# Output will return " False " as the variable " a ", which is 
# assigned to the value “ 10 ” is already present in the 
# dictionary “ dict ”.

Output

Here, as we can see, a dictionary is declared with three elements in it. Then a statement is written with “not in” operator and the dictionary. The output returns the Boolean value “False” as the element that has its key as “a” is present in the dictionary. The statement written says that the key “a” does not belong to the dictionary, but “a” actually belongs to the declared dictionary iterator. So, considering this case, the output returned the value “False”.

Using NOT IN on Range function

The “ not in ” operator can be used in a statement containing a range function as an iterator. Firstly, the range of the function is defined, and the range function is declared. Then a statement containing the " not in " operator is used, and the output will return a Boolean value depending on the case and condition.

Example of NOT IN on Range function

# the declaration of a range function in python.
x = range(4)


# statement using the " not in " operator.
print(5 not in x)


# Output will return " True " as five is not within the range of 
# 4.

Output

Here, as we can see, a range function is declared with four as its range, i.e., the function contains elements ranging from “0” to “3”. Then a statement is written with “not in” operator and the range function. The output is “True” as the element “5” is not present in the range function. The statement written says that " 5 " does not belong to the range function, so the output of the above program returns the Boolean value “True”.

Using NOT IN on an Array

The “not in” operator can be used in a statement containing an array as an iterator. Firstly, the values are stored in an array, and the array is declared. Then a statement containing the " not in " operator is used, and the output will return a Boolean value.

Example of NOT IN on an Array:

# importing array module to the python program application
import array as arr 


# initializing the array with four elements in it.
a = arr.array('i', [2, 4, 6, 8])


# statement using the " not in " operator.
print(2 not in a)


# Output will return " False " as two are involved within the 
# array.

Output

Here, as we can see, an array is declared with four elements in it. Then a statement is written with “not in” operator and the declared array. The output is “False” as the element “2 ” is present in the declared array “ a ”. The statement written says that “2 " does not belong to the array, so the output returns the Boolean value “False” since two is already declared within the array " arr ". With this, we can conclude that the statement given is false, so the output returned False.

Using NOT IN on a String

The “ not in ” operator can be used in a statement containing a string as an iterator. Firstly, the values are stored in a string, and the string is declared. Then a statement containing the " not in " operator is used, and the output will return a Boolean value.

Example 1:  NOT IN on a String

# this is a code to show the working of “ not in” operator on a string.


# the declaration of a string in python.
x = 'happy'


# statement using the " not in " operator.
print('g' not in x)


# Output will return " True ".

Output

Here, as we can see, a string is declared with six elements in it. Then a statement is written with “ not in ” operator and the declared string. The output is “ True ” as the element “ g ” is not present in the declared string “ x ”. The statement written says that “ g " does not belong to the string, so the output returns the boolean value "  True ".

Example 2:  NOT IN on a String:

# this is a code to show the working of “ not in” operator on a string.


# declaration of a string in python.
x = 'happy'


# statement using the " not in " operator.
print(3 not in x)


# the output returns an error.

The output of the program:

From the above program and its output, we can conclude that the " not in " operator can be used on a string only when the element given as input to check whether it is present in the string or not is also a string. When an integer such as " 3 " is given, the statement returns an error as " x " is a string.

Note: The “not in” operator works fastest on sets and dictionaries when compared with other iterators.