Reference library

Comprehensions & generators

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

5 matches

Dict Comprehension to Map Keys to Lengths in Python

Build a dictionary that maps each word to its character count using a dictionary comprehension.

words = ["apple", "banana", "cherry", "date", "elderberry"]

word_lengths = {word: len(word) for word in words}

print(word_lengths)

14 0 Open

Comprehensions & generators easy

How to Generate Combinations with Replacement in Python

Generate all r-length combinations with repetition from a list using the standard library itertools.combinations_with_replacement function.

itertools combinations generator

Python

from itertools import combinations_with_replacement

items = ['A', 'B', 'C']
r = 2

combos = list(combinations_with_replacement(items, r))

for combo in combos:
    print(combo)

if __name__ == "__main__":
    print(f"Total combinations with replacement: {len(combos)}")

11 0 Open

Comprehensions & generators easy

How to Generate Permutations of Length r in Python

Generate all ordered arrangements of length r from a given list of elements using itertools.permutations.

permutations itertools combinatorics

Python

from itertools import permutations

def generate_permutations(elements, r):
    """Generate all r-length permutations of the given elements."""
    return list(permutations(elements, r))

if __name__ == "__main__":
    elements = ['A', 'B', 'C']
    r = 2
    result = generate_permutations(elements, r)
    print(f"Ele…

14 0 Open

Comprehensions & generators easy

How to Implement the Iterator Protocol in Python

A manual iterator class using __iter__ and __next__, compared with an equivalent generator using yield.

iterator generator protocol

Python

class ManualCounter:
    def __init__(self, limit):
        self.limit = limit
        self.current = 0

    def __iter__(self):
        return self

    def __next__(self):
        if self.current >= self.limit:
            raise StopIteration
        value = self.current
        self.current += 1
        return valu…

13 0 Open

Comprehensions & generators easy

Set Comprehension for Unique Word Lengths in Python

Use a set comprehension to extract unique word lengths from a string, then sort and print the result.

set comprehension unique word lengths

Python

text = "hello world hello python programming"

word_lengths = {len(word) for word in text.split()}

print("Unique word lengths:", word_lengths)
print("Sorted:", sorted(word_lengths))

10 0 Open

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