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Comprehensions & generators

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

53 matches

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

Python Generator to Filter Duplicates with a Seen Set

A lazily-evaluated generator function that yields only the first occurrence of each item, using a set to track seen values.

generator dedupe set

Python

def unique_generator(items):
    seen = set()
    for item in items:
        if item not in seen:
            seen.add(item)
            yield item

if __name__ == "__main__":
    data = [1, 2, 2, 3, 3, 3, 4, 5, 5]
    result = list(unique_generator(data))
    print(result)

14 0 Open

Comprehensions & generators easy

Sum of Squares with a Generator Expression in Python

This code computes the sum of squares of integers from 1 to n using a generator expression, demonstrating a memory-efficient and concise way to aggregate a sequence.

generator sum squares

Python

def sum_of_squares(n):
    return sum(x * x for x in range(1, n + 1))

if __name__ == "__main__":
    print(f"Sum of squares from 1 to 5: {sum_of_squares(5)}")
    print(f"Sum of squares from 1 to 10: {sum_of_squares(10)}")

14 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

Comprehensions & generators easy

Write Data Helpers with Comprehensions and Generators in Python

Demonstrates list, dict, and set comprehensions plus generator expressions and generator functions for building concise data helpers.

comprehensions generators data-helpers

Python

# Basic comprehensions and generators demo

# List comprehension: squares of evens
squares = [x * x for x in range(10) if x % 2 == 0]
print("List comp:", squares)

# Dictionary comprehension: char -> count
text = "hello"
char_counts = {c: text.count(c) for c in set(text)}
print("Dict comp:", char_counts)

# Set compre…

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