Python Identity Operators

Unveiling Identity Operators in Python

Identity operators in Python are essential tools for comparing the memory addresses of objects. These operators, is and is not, evaluate whether two variables reference the same object or not. Understanding identity operators is crucial for dealing with object references and managing memory effectively in Python programming. In this comprehensive guide, we’ll delve into the world of identity operators, their syntax, and their applications.

Note

Identity operators are also known as comparison operators. It is because they compare the memory locations of two objects. They don’t compare the values of two objects.

The following table lists the identity operators in Python:

Operator	Description	Example
is	Returns True if both variables are the same object	x is y
is not	Returns True if both variables are not the same object	x is not y

is Operator

is Operator

The is operator returns True if both variables are the same object. It returns True if both variables point to the same memory location otherwise False. The following example demonstrates how to use the is operator in Python:

operators.py

# is operator
x = 10
y = 10
z = x is y
print(z)

Output:

command

C:\Users\Your Name> python operators.py
True

In the above example, we have used the is operator to check if the value of x is the same as the value of y. Since the value of x is the same as the value of y, the condition becomes True. The result of the is operator is then assigned to the variable z. The value of z is then printed to the console.

Note

In python, all the variables are references to the objects. When we assign a value to a variable, we are actually binding the variable to the object. The is operator compares the memory locations of two objects. If both variables point to the same memory location, the is operator returns True otherwise False.

When we assign a value to a variable, the Python interpreter creates an object and binds the variable to that object. If we create another variable and assign the same value to it, the Python interpreter assigns the same object to the new variable. In this case, both variables point to the same object. The is operator returns True in this case.

operators.py

a = 10 # Location: 0x0001
b = 10 # Location: 0x0001
print(a is b)

However, if we create another variable and assign a different value to it, the Python interpreter creates a new object and binds the new variable to that object. In this case, both variables point to different objects. The is operator returns False in this case.

operators.py

a = 10 # Location: 0x0001
b = 20 # Location: 0x0002
print(a is b)

In the case, if you assign one variable to another variable, both variables point to the same object. The is operator returns True in this case.

operators.py

a = 10 # Location: 0x0001
b = a  # Location: 0x0001
print(a is b)

For more details about memory management in Python, please refer to the Python Management.

is not Operator

is not Operator

The is not operator returns True if both variables are not the same object. It returns True if both variables point to different memory locations otherwise False. The following example demonstrates how to use the is not operator in Python:

operators.py

# is not operator
x = 10
y = 5
z = x is not y
print(z)

Output:

command

C:\Users\Your Name> python operators.py
True

In the above example, we have used the is not operator to check if the value of x is not the same as the value of y. Since the value of x is not the same as the value of y, the condition becomes True. The result of the is not operator is then assigned to the variable z. The value of z is then printed to the console.

Identity Operators with Lists

The identity operators can be used with lists. The following example demonstrates how to use the identity operators with lists in Python:

operators.py

# Identity operators with lists
x = [1, 2, 3, 4, 5]
y = 10
z = y is x
t = y is not x
print(z)
print(t)

Output:

command

C:\Users\Your Name> python operators.py
False
True

In the above example, we have used the is operator to check if the value of x is the same as the value of y. Since the value of x is not the same as the value of y, the condition becomes False. The result of the is operator is then assigned to the variable z. The value of z is then printed to the console.

In the above example, we have used the is not operator to check if the value of x is not the same as the value of y. Since the value of x is not the same as the value of y, the condition becomes True. The result of the is not operator is then assigned to the variable t. The value of t is then printed to the console.

Another example of using the identity operators with lists is given below:

operators.py

# Identity operators with lists
x = [1, 2, 3, 4, 5]
y = [1, 2, 3, 4, 5]
z = x is y
t = x is not y
print(z)
print(t)
# After changing the value of y
y = x
y[0] = 10
z = x is y
t = x is not y
print(z)
print(t)

Output:

command

C:\Users\Your Name> python operators.py
False
True
True
False

In the above example, we have used the is operator to check if the value of x is the same as the value of y. Since the value of x is not the same as the value of y, the condition becomes False. The result of the is operator is then assigned to the variable z. The value of z is then printed to the console.

In the above example, we have used the is not operator to check if the value of x is not the same as the value of y. Since the value of x is not the same as the value of y, the condition becomes True. The result of the is not operator is then assigned to the variable t. The value of t is then printed to the console.

In the above example, we have assigned the value of x to y. Since both variables point to the same object, the is operator returns True and the is not operator returns False.

Identity Operators with Strings

The identity operators can be used with strings. The following example demonstrates how to use the identity operators with strings in Python:

operators.py

# Identity operators with strings
x = "Hello"
y = "Hello"
z = x is y
t = x is not y
print(z)
print(t)
# After changing the value of y
y = "World"
z = x is y
t = x is not y
print(z)
print(t)

Output:

command

C:\Users\Your Name> python operators.py
True
False
False
True

In the above example, we have used the is operator to check if the value of x is the same as the value of y. Since the value of x is the same as the value of y, the condition becomes True. The result of the is operator is then assigned to the variable z. The value of z is then printed to the console.

In the above example, we have used the is not operator to check if the value of x is not the same as the value of y. Since the value of x is the same as the value of y, the condition becomes False. The result of the is not operator is then assigned to the variable t. The value of t is then printed to the console.

In the above example, we have assigned the value of x to y. Since both variables point to the same object, the is operator returns True and the is not operator returns False.

sketch is compares identity; == compares value p5.js Pause Restart

They agree often enough to hide the bug and disagree exactly where it hurts. Python caches small integers from -5 to 256, so two separately computed 256s really are the same object and is returns True -- then 257 returns False with no warning. Strings behave the same way: identical literals share an object, and constant folding covers simple concatenation, but a string genuinely assembled at runtime is a different object with equal contents. All values below were checked in the interpreter.

Comparison Operators vs Identity Operators

The comparison operators and identity operators are different. The comparison operators compare the values of two objects. The identity operators compare the memory locations of two objects. The following example demonstrates the difference between the comparison operators and identity operators in Python:

operators.py

# Comparison operators vs Identity operators
x = [1, 2, 3, 4, 5]
y = [1, 2, 3, 4, 5]
z = x == y
t = x is y
print(z)
print(t)

Output:

command

C:\Users\Your Name> python operators.py
True
False

In the above example, we have used the == operator to check if the value of x is the same as the value of y. Since the value of x is the same as the value of y, the condition becomes True. The result of the == operator is then assigned to the variable z. The value of z is then printed to the console.

In the above example, we have used the is operator to check if the value of x is the same as the value of y. Since the value of x is not the same as the value of y, the condition becomes False. The result of the is operator is then assigned to the variable t. The value of t is then printed to the console.

Conditional Statements with Identity Operators

The identity operators can be used in conditional statements. The following example demonstrates how to use the identity operators in conditional statements in Python:

operators.py

# Conditional statements with identity operators
x = 10
y = 5
if x is y:
    print("x is y")
else:
    print("x is not y")

Output:

command

C:\Users\Your Name> python operators.py
x is not y

In the above example, we have used the is operator in the conditional statement. Since the value of x is not the same as the value of y, the condition becomes False. The else block is executed in this case.

Conclusion

Identity operators in Python provide a powerful mechanism for comparing object identity and avoiding unintended side effects in your code. Whether you’re checking for None, ensuring variables reference the same object, or managing mutable objects, is and is not offer a precise and efficient way to handle object identity.

As you progress in your Python programming journey, experiment with identity operators, understand their use cases, and incorporate them into your code where needed. For more insights and practical examples, check out our tutorials on Python Central Hub!

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Try it: Identity Operators Exercises

Exercise 1 – is Operator

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Exercise 2 – is not

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Exercise 3 – id() Function

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