In today's article, we will see how to swap the values of two variables in Python. More importantly, we will understand why this works.

Traditionally, variable swapping in any language involves the introduction of a temporary variable to hold a value.

x = 1
y = 2

temp = x
x = y
y = temp

# Will output x = 2
print(f"x = {x}")

# Will output y = 1
print(f"y = {y}")

Python can do this in one line.

x, y = y, x

The output will be as expected.

# Will output x = 2
print(f"x = {x}")

# Will output y = 1
print(f"y = {y}")

Why does this work?

To understand why this works, we need to delve into the world of tuples. Tuples are immutable data structures in Python. Traditionally, a tuple is represented as x = (1, 2). Its elements can be accessed using the index values.

x = (1, 2)

# Will output 1
print(x[0])

# Will result in an error
# 'tuple' object does not support item assignment

x[0] = 2

While we usually represent tuples using () brackets, a tuple can also be written as x = 1, 2.

x = 1, 2

# Will output <class 'tuple'>
print(type(x))

In addition to using the index values, we can extract values from tuples by using the unpacking syntax.

x, y = 1, 2

# Will output x = 1, y = 2
print(f"x = {x}, y = {y}")

x, y, *z = 1, 2, 3, 4

# Will output x = 1, y = 2, z = [3, 4]
print(f"x = {x}, y = {y}, z = {z}")

We can, therefore, use the unpacking method to swap variables as well.

x, y = 1, 2

# Will output y, x = 2, 1
print(f"y, x = {y}, {x}")

# Variables are swapped!
x, y = y, x