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https://github.com/n8brooks/combinatorics
🦕 Combinatorial generators including combinations, permutations, combinations with replacement, permutations with replacement, cartesian products, and power sets.
https://github.com/n8brooks/combinatorics
cartesian-product combinations combinations-with-repetition combinatorics deno npm permutations permutations-with-repetition typescript
Last synced: 7 days ago
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🦕 Combinatorial generators including combinations, permutations, combinations with replacement, permutations with replacement, cartesian products, and power sets.
- Host: GitHub
- URL: https://github.com/n8brooks/combinatorics
- Owner: N8Brooks
- License: mit
- Created: 2021-09-28T05:52:04.000Z (about 3 years ago)
- Default Branch: main
- Last Pushed: 2022-07-06T04:28:42.000Z (over 2 years ago)
- Last Synced: 2024-12-09T18:46:35.934Z (17 days ago)
- Topics: cartesian-product, combinations, combinations-with-repetition, combinatorics, deno, npm, permutations, permutations-with-repetition, typescript
- Language: TypeScript
- Homepage: https://deno.land/x/combinatorics
- Size: 112 KB
- Stars: 26
- Watchers: 1
- Forks: 2
- Open Issues: 3
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# combinatorics
[](https://doc.deno.land/https/deno.land/x/combinatorics/mod.ts)
[](https://codecov.io/gh/N8Brooks/combinatorics)
[](https://github.com/N8Brooks/combinatorics/actions/workflows/cd.yml)
[](https://github.com/N8Brooks/combinatorics/actions/workflows/ci.yml)
This module provides generators for iterating subsets of an input. It is heavily
inspired by the combinatorial iterators provided by the
[itertools](https://docs.python.org/3/library/itertools.html) 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
### combinations
Yields `r` length `Arrays` from the input `iterable`. Order of selection does
not matter and elements are chosen without replacement.
```ts
import { assertEquals } from "https://deno.land/std/testing/asserts.ts";
import { combinations } from "https://deno.land/x/combinatorics/mod.ts";
const sequences = [...combinations([1, 2, 3, 4], 2)];
assertEquals(sequences, [
[1, 2],
[1, 3],
[1, 4],
[2, 3],
[2, 4],
[3, 4],
]);
```
### permutations
Yields `r` length `Arrays` from the input `iterable`. Order of selection is
important and elements are chosen without replacement. If `r` is undefined, then
the length of the `iterable` is used.
```ts
import { assertEquals } from "https://deno.land/std/testing/asserts.ts";
import { permutations } from "https://deno.land/x/combinatorics/mod.ts";
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],
]);
```
### combinationsWithReplacement
Yields `r` length `Arrays` from the input `iterable`. Order of selection is not
important and elements are chosen with replacement.
```ts
import { assertEquals } from "https://deno.land/std/testing/asserts.ts";
import { combinationsWithReplacement } from "https://deno.land/x/combinatorics/mod.ts";
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],
]);
```
### permutationsWithReplacement
Yields `r` length `Arrays` from the input `iterable`. Order of selection is
important and elements are chosen with replacement.
```ts
import { assertEquals } from "https://deno.land/std/testing/asserts.ts";
import { permutationsWithReplacement } from "https://deno.land/x/combinatorics/mod.ts";
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],
]);
```
### cartesianProduct
Roughly equivalent to running nested `for...of` loops using one of the inputs to
provide the element at each index for the yielded `Array`.
```ts
import { assertEquals } from "https://deno.land/std/testing/asserts.ts";
import { cartesianProduct } from "https://deno.land/x/combinatorics/mod.ts";
const sequences = [...cartesianProduct([1, 2, 3], [4, 5, 6], [7, 8, 9])];
assertEquals(sequences, [
[1, 4, 7], [1, 4, 8], [1, 4, 9],
[1, 5, 7], [1, 5, 8], [1, 5, 9],
[1, 6, 7], [1, 6, 8], [1, 6, 9],
[2, 4, 7], [2, 4, 8], [2, 4, 9],
[2, 5, 7], [2, 5, 8], [2, 5, 9],
[2, 6, 7], [2, 6, 8], [2, 6, 9],
[3, 4, 7], [3, 4, 8], [3, 4, 9],
[3, 5, 7], [3, 5, 8], [3, 5, 9],
[3, 6, 7], [3, 6, 8], [3, 6, 9],
]);
```
### powerSet
The set of all subsets of the given `iterable`. Equivalent to running
`combinations` with `0 <= r <= iterable.length` and flattening the results. The
first subset is the empty set given when `r = 0`.
```ts
import { assertEquals } from "https://deno.land/std/testing/asserts.ts";
import { powerSet } from "https://deno.land/x/combinatorics/mod.ts";
const sequences = [...powerSet([1, 2, 3])];
assertEquals(sequences, [
[],
[1],
[2],
[3],
[1, 2],
[1, 3],
[2, 3],
[1, 2, 3],
]);
```