Reference library

Comprehensions & generators

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

3 matches

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.

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

Merge Data with Comprehension and Generator in Python

Merge user and order data using a dictionary comprehension for lookups and a generator expression to filter and transform orders.

dictionary-comprehension generator-expression data-merging

Python

def merge_data(users, orders):
    """
    Merge user and order data using a dictionary comprehension
    and a generator expression for filtering.
    """
    # Build a lookup: user_id -> user name
    user_map = {user["id"]: user["name"] for user in users}

    # Generator: yield orders with user names attached
    …

14 0 Open

Comprehensions & generators medium

Merge Sorted Iterators with a Heap Generator in Python

Merge multiple sorted iterators into a single sorted stream using a heap and generator, yielding values lazily in order.

heapq generator merge

Python

import heapq

def merge_sorted_iterators(*iterators):
    heap = []
    for idx, iterator in enumerate(iterators):
        try:
            value = next(iterator)
            heapq.heappush(heap, (value, idx, iterator))
        except StopIteration:
            continue

    while heap:
        value, idx, iterator = …

15 0 Open

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