Python – Bitwise OR among list elements

The bitwise OR operation combines the binary representations of numbers using the "|" operator. In Python, you can perform bitwise OR among all elements in a list using several approaches including iteration, lambda functions, and NumPy.

Understanding Bitwise OR

The bitwise OR operator "|" compares each bit position and returns 1 if at least one of the corresponding bits is 1 ?

# Example: 40 | 50
# 40 in binary: 101000
# 50 in binary: 110010
# Result:       111010 (which is 58 in decimal)

print(f"40 | 50 = {40 | 50}")
print(f"Binary result: {bin(40 | 50)}")

40 | 50 = 58
Binary result: 0b111010

Using Iteration Method

The simplest approach uses a for loop to iterate through all elements ?

# Initialize the list with integer elements
numbers = [40, 50, 90]

# Start with 0 (neutral element for OR operation)
result = 0

# Perform bitwise OR with each element
for num in numbers:
    result |= num

print(f"Bitwise OR result: {result}")
print(f"Binary representation: {bin(result)}")

Bitwise OR result: 122
Binary representation: 0b1111010

Using Lambda with reduce()

The functional approach uses reduce() with a lambda function ?

from functools import reduce

# Initialize the list with integer elements
numbers = [40, 50, 90]

# Use lambda function with reduce to perform bitwise OR
result = reduce(lambda a, b: a | b, numbers)

print(f"Bitwise OR result: {result}")
print(f"Binary representation: {bin(result)}")

Bitwise OR result: 122
Binary representation: 0b1111010

Using NumPy Module

NumPy provides a built-in function for bitwise operations ?

import numpy as np

# Initialize the list with integer elements
numbers = [40, 50, 90]

# Use NumPy's bitwise_or.reduce() function
result = np.bitwise_or.reduce(numbers)

print(f"Bitwise OR result: {result}")

Bitwise OR result: 122

Performance Comparison

Working Example with Different Values

# Demonstrate with different numbers
data = [12, 25, 30]

print("Individual binary representations:")
for num in data:
    print(f"{num}: {bin(num)}")

# Calculate step by step
step1 = 12 | 25  # 12 OR 25
step2 = step1 | 30  # result OR 30

print(f"\nStep-by-step calculation:")
print(f"12 | 25 = {step1}")
print(f"{step1} | 30 = {step2}")
print(f"Final result: {step2}")

Individual binary representations:
12: 0b1100
25: 0b11001
30: 0b11110

Step-by-step calculation:
12 | 25 = 29
29 | 30 = 31
Final result: 31

Conclusion

Use iteration for simple cases and better readability. The reduce() approach is more functional, while NumPy is optimal for large datasets. All methods produce the same result by combining bits using the OR operation.