itertools

This module provides generators for iterating subsets of an input. It is heavily inspired by the combinatorial iterators provided by the itertools package from the Python standard library.

• All generators are importable on their own.
• These implementations do not build up intermediate results in memory.
• All functions iterate subsets lexicographically according to their input indices. If the input is sorted the output will be too.
• Likewise, whether the input elements are unique or not does not matter.
• The inputs provided are not modified, however, consumable iterables will be consumed.

Usage

Simple Combinations

Returns r-length subsequences of elements from the input iterable. Order of selection does not matter and elements are chosen without replacement.

import { assertEquals } from "@std/assert";
import { combinations } from "jsr:@gabelluardo/itertools";

const sequences = [...combinations([1, 2, 3, 4], 2)];

assertEquals(sequences, [
  [1, 2],
  [1, 3],
  [1, 4],
  [2, 3],
  [2, 4],
  [3, 4],
]);

Simple Permutations

Returns successive r-length permutations of elements from the iterable.

import { assertEquals } from "@std/assert";
import { permutations } from "jsr:@gabelluardo/itertools";

const sequences = [...permutations([1, 2, 3, 4], 2)];

assertEquals(sequences, [
  [1, 2],
  [1, 3],
  [1, 4],
  [2, 1],
  [2, 3],
  [2, 4],
  [3, 1],
  [3, 2],
  [3, 4],
  [4, 1],
  [4, 2],
  [4, 3],
]);

Combinations with Replacement

Returns r-length subsequences of elements from the input iterable allowing individual elements to be repeated more than once.

import { assertEquals } from "@std/assert";
import { combinationsWithReplacement } from "jsr:@gabelluardo/itertools";

const sequences = [...combinationsWithReplacement([1, 2, 3, 4], 2)];

assertEquals(sequences, [
  [1, 1],
  [1, 2],
  [1, 3],
  [1, 4],
  [2, 2],
  [2, 3],
  [2, 4],
  [3, 3],
  [3, 4],
  [4, 4],
]);

Permutations with Replacement

Returns successive r-length permutations of elements from the iterable allowing individual elements to be repeated more than once.

import { assertEquals } from "@std/assert";
import { permutationsWithReplacement } from "jsr:@gabelluardo/itertools";

const sequences = [...permutationsWithReplacement([1, 2, 3, 4], 2)];

assertEquals(sequences, [
  [1, 1],
  [1, 2],
  [1, 3],
  [1, 4],
  [2, 1],
  [2, 2],
  [2, 3],
  [2, 4],
  [3, 1],
  [3, 2],
  [3, 3],
  [3, 4],
  [4, 1],
  [4, 2],
  [4, 3],
  [4, 4],
]);