Python Membership and Identity Operators

Membership Operators

Membership operators are operators used to validate the membership of a value. It test for membership in a sequence, such as strings, lists, or tuples.

1. in operator : The ‘in’ operator is used to check if a value exists in a sequence or not. Evaluates to true if it finds a variable in the specified sequence and false otherwise.

# Python program to illustrate
# Finding common member in list
# using 'in' operator
list_1=[1,2,3,4,5]
list2=[6,7,8,9]
for item in list_1:
if item in list2:
print("overlapping")
else:
print("not overlapping")
Output:

not overlapping
Same example without using in operator:

# Python program to illustrate
# Finding common member in list
# without using 'in' operator

# Define a function() that takes two lists
def overlapping(list_1,list2):

c=0
d=0
for i in list_1:
c+=1
for i in list2:
d+=1
for i in range(0,c):
for j in range(0,d):
if(list_1[i]==list2[j]):
return 1
return 0
list_1=[1,2,3,4,5]
list2=[6,7,8,9]
if(overlapping(list_1,list2)):
print("overlapping")
else:
print("not overlapping")
Output:

not overlapping
2. ‘not in’ operator- Evaluates to true if it does not finds a variable in the specified sequence and false otherwise.

# Python program to illustrate
# not 'in' operator
x = 24
y = 20
list = [10, 20, 30, 40, 50 ];

if ( x not in list ):
print("x is NOT present in given list")
else:
print("x is present in given list")

if ( y in list ):
print("y is present in given list")
else:
print("y is NOT present in given list")

Identity operators

In Python are used to determine whether a value is of a certain class or type. They are usually used to determine the type of data a certain variable contains.
There are different identity operators such as

1. ‘is’ operator – Evaluates to true if the variables on either side of the operator point to the same object and false otherwise.

# Python program to illustrate the use
# of 'is' identity operator
x = 5
if (type(x) is int):
print("true")
else:
print("false")
Output:

true

2. ‘is not’ operator – Evaluates to false if the variables on either side of the operator point to the same object and true otherwise.

# Python program to illustrate the
# use of 'is not' identity operator
x = 5.2
if (type(x) is not int):
print("true")
else:
print("false")
Output:

true