Python – Product of squares in list

The product of squares in a list means calculating the square of each element first, then multiplying all the squared values together. Python provides multiple approaches to solve this problem efficiently.

Understanding the Problem

Given a list like [9, -4, 8, -1], we need to ?

• Square each element: 9² = 81, (-4)² = 16, 8² = 64, (-1)² = 1
• Multiply all squares: 81 × 16 × 64 × 1 = 82944

Method 1: Using Iteration

Iterate through each element, square it, and multiply with the running product ?

# Initialize the list with integer elements
numbers = [9, -4, 8, -1]

# Initialize product to 1 (multiplying by 1 preserves the value)
product = 1

# Iterate through the list
for num in numbers:
    # Calculate square and multiply with product
    product *= num ** 2

print("Product of squares:", product)

Product of squares: 82944

Method 2: Using functools.reduce()

Use reduce() with a lambda function to multiply all squared values ?

from functools import reduce

# Initialize the list
numbers = [9, -4, 8, -1]

# Use reduce with lambda to multiply all squared values
product = reduce(lambda a, b: a * b, [x**2 for x in numbers])

print("Product of squares:", product)

Product of squares: 82944

Method 3: Using math.prod() (Python 3.8+)

The most concise approach using the built-in math.prod() function ?

import math

numbers = [9, -4, 8, -1]

# Calculate product of squares using math.prod()
product = math.prod(x**2 for x in numbers)

print("Product of squares:", product)

Product of squares: 82944

Comparison

Conclusion

Use math.prod() for the cleanest solution in Python 3.8+. For older versions, iteration provides the most readable approach. All methods have O(n) time complexity.