Identity and Membership Operators

Special Operators

Python language offers some special type of operators like the identity operator or the membership operator. They are described below with examples.

Identity Operators

Identity operators are used to compare the memory locations of two objects.

'is' and 'is not' are the identity operators in Python

Output will be boolean value ( TRUE or FALSE)

Note: For understanding purpose retriving id details (i.e) memory allocation. But in real time you can directly use 'is' operator. No need to verify the memory address.

# Example 1 - Numbers using 'is' operator
x = 10
print("memory location of x is",id(x))

y = 10
print("memory location of y is",id(y))

print (x is y) #10 is object created once both x and y points to same object

Output:
memory location of x is 140708939362336
memory location of y is 140708939362336
True

# Example 2 - String using 'is' operator
a = "Python"
print("memory location of a is",id(a))

b = "Python"
print("memory location of b is",id(b))

# "Python" is object created once both a and b points to same object
print (a is b)

Output:
memory location of a is 2332982898792
memory location of b is 2332982898792
True

# Example 3  - List using 'is' operator
l1 = [1,2,3,4]
print("memory location of l1 is",id(l1))

l2 = [1,2,3,4]
print("memory location of l2 is",id(l2))

print (l1 is l2) # list l1 and l1 will create a separate objects 

Output:
memory location of l1 is 2333051991112
memory location of l2 is 2333042340296
False

# Example 4 - Numbers using 'is not' operator
x = 10
y = 10
print (x is not y) 

a = 20 
b = 15

print(a is not b)

Output:
False
True

# Example 5 - String using 'is not' operator
s1 = "Python"
s2 = "Python"
print (s1 is not s2) 

s3 = "Python"
s4 = "Java"
print (s3 is not s4) 

Output:
False
True

# Example 6  - List using 'is' operator
l1 = [1,2,3,4]
l2 = [1,2,3,4]
print (l1 is not l2) 

Output:
True

Conclusion:
'is' operator will display true if the memory address is same and
'is not' operator will display true if the memory address is different.

Membership Operators

Membership operators are used to verify whether a value or variable is found in a sequence (Eg: string, list, tuple and dictionary)

'in' and 'not in' are the membership operators in Python.

Output will be boolean value ( TRUE or FALSE)

# Example 1 - List using 'in' operator
mylist = [1,2.5,"Python",10]
print(10 in mylist)
print("Python" in mylist)
print(5 in mylist)

Output:
True
True
False

# Example 2 - List using 'not in' operator
mylist2 = [1,12.5,"Java",35]
print(10 not in mylist2)
print("Java" not in mylist2)

Output:
True
False

Conclusion:
'in' operator will display true if the value is found in the sequence and
'not in' operator will display true if the value is not found in the sequence.