Identity vs Equality in Python

 This topic is extremely important if you are learning Python as a beginner. 

Golden Rule

• == → compares values

• is → compares memory identity

Example 1:

In the following example, even though values are the same, a and b are different objects in memory.

a = [1, 2, 3]

b = [1, 2, 3]

print(a == b)  # True

print(a is b)  # False

Example 2:

In this example, a and b are equal and as well as identical. This is because Python reuses small integers to optimize memory usage which is known as Integer Interning.

a = 256

b = 256

print(a == b) # False

print(a is b)  # True

Example 3:

The same logic applies to string values since Python reuses small string values to optimize memory usage as well.

a = "hello"

b = "hello"

print(a is b)  # True

Example 4:

In the following example, the values are equal  but they are different objects.

a = "".join(["he", "llo"])

b = "hello"

print(a is b)  # False