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Comprehensions & generators

List/dict/set comprehensions, generator expressions, and lazy iteration.

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How to Use starmap() to Unpack Tuple Arguments in Python

Use itertools.starmap to apply a function to each tuple in an iterable, unpacking tuple elements as separate arguments and returning an iterator of results.

itertools starmap generators

Python

from itertools import starmap

def multiply(a, b):
    return a * b

if __name__ == "__main__":
    pairs = [(2, 3), (4, 5), (6, 7), (8, 9)]
    results = list(starmap(multiply, pairs))
    print(results)

14 0 Open

Comprehensions & generators easy

How to generate combinations in Python with itertools

Generate all unique combinations of r items from a given list using itertools.combinations.

itertools combinations generators

Python

import itertools

def combinations_generator(items, r):
    return list(itertools.combinations(items, r))

if __name__ == "__main__":
    items = ['A', 'B', 'C', 'D']
    r = 2
    result = combinations_generator(items, r)
    for combo in result:
        print(combo)
    print(f"Total: {len(result)} combinations of {…

14 0 Open

Comprehensions & generators easy

How to skip items until a condition is met in Python

Use itertools.dropwhile to skip leading elements while a predicate returns true, then yield the rest of the sequence unchanged.

itertools generators dropwhile

Python

def is_negative(x):
    return x < 0

numbers = [-3, -1, 0, 5, 2, -8, 7]
result = list(itertools.dropwhile(is_negative, numbers))
print(f"Original: {numbers}")
print(f"After dropwhile: {result}")

13 0 Open

Comprehensions & generators easy

List Comprehension to Filter Even Numbers in Python

Creates a new list containing only the even numbers from an existing list using a list comprehension with a condition.

list comprehension filtering even numbers

Python

numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
even_numbers = [n for n in numbers if n % 2 == 0]
print(f"Original: {numbers}")
print(f"Even numbers: {even_numbers}")

13 0 Open

Comprehensions & generators easy

Python Comprehensions and Generators for Beginners

Learn list, dict, and set comprehensions plus generator expressions and generator functions with clear, runnable examples.

comprehensions generators lazy-evaluation

Python

# Demonstrates list comprehensions, dict comprehensions, set comprehensions, and generators

def demonstrate_comprehensions():
    # List comprehension: squares of even numbers
    numbers = range(1, 11)
    even_squares = [n ** 2 for n in numbers if n % 2 == 0]
    
    # Dict comprehension: number to its factorial
 …

15 0 Open

Comprehensions & generators easy

Take n items from an infinite Python generator

Uses itertools.islice to lazily take exactly n items from an infinite generator without exhausting it.

generators itertools islice

Python

from itertools import islice

def count_up_from(start=0):
    n = start
    while True:
        yield n
        n += 1

def take_n(generator, count):
    return list(islice(generator, count))

if __name__ == "__main__":
    gen = count_up_from(10)
    result = take_n(gen, 5)
    print(result)

11 0 Open

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