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How to flip 1 and 0 in Python

Sometimes in a Python program, you will need to swap 0 and 1 and you would like to do it in a Python-ic way. What is a Pythonic way you ask? And when would you need to so such swaps?

For instance, in low-level programming or when working with binary data, you might need to flip specific bits. Swapping 0 and 1 is essentially flipping a single bit.

In binary image processing, swapping 0 and 1 can invert black and white pixels, creating a negative of the image.

In game logic, swapping 0 and 1 can be used to toggle states, such as turning features on or off or switching between player turns.

We will see five different ways to swap 0 and 1 in Python!

Method 1: Subtraction

The simplest method to swap 0 and 1 is by subtracting the value from 1:

def swap(val):
    return 1 - val

This works because 1 - 0 = 1 and 1 - 1 = 0.

Method 2: XOR operator

The XOR (exclusive or) operation can be used to flip bits:

def swap(val):
    return val ^ 1

This method is efficient and works by flipping the least significant bit.

Method 3: Boolean Negation

By converting the value to a boolean and negating it, we can swap 0 and 1:

def swap(val):
    return int(not bool(val))

This method first converts the value to a boolean (False for 0, True for 1), negates it, and then converts it back to an integer.

Method 4: Dictionary

A dictionary can be used to create a lookup table for swapping:

swap = {0: 1, 1: 0}

def swap_value(val):
    return swap[val]

This method is clear and easily extensible if more values need to be swapped in the future.

Method 4: Lambda Function

A concise lambda function can be used to swap the values:

swap = lambda x: 1 if x == 0 else 0

This one-liner checks if the input is 0 and returns 1, otherwise it returns 0.

Understanding when and how to swap 0 and 1 is thus valuable in various programming contexts, from low-level bit manipulation to high-level application logic.

If you liked this blogpost, checkout our blogpost on how to make a number negative in Python which has similarly multiple ways to solve the same problem! Also see our blogpost on integers and their representations!

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