indices-permutations

is a recursive reducer to all permutations with repetitions of multi dimensional array indices

Installation | Usage | Examples | License

Installation

With npm do

npm install indices-permutations

Usage

Use it as a callback for the Array.prototype.reduce() on an array of positive integers. It returns the result array of all indices permutated.

Note that initialValue argument must be provided, for instance it can be an empty array [].

Both CommonJS and ES6 import syntax are supported.

import indicesPermutations from 'indicesPermutations'

const indicesPermutations = require('indices-permutations')

Examples

All code in the examples below is intended to be contained into a single file.

order 1

Reduce [n] to [[0], [1], ..., [n-1]]

[5].reduce(indicesPermutations, []) // [[0], [1], [2], [3], [4]]

order 2

Reduce [m, n] to [[0, 0], [0, 1], ... ,[m-1, n-1]]

[3, 3].reduce(indicesPermutations, []) // [[0, 0], [0, 1], [0, 2],
                                       //  [1, 0], [1, 1], [1, 2],
                                       //  [2, 0], [2, 1], [2, 2]]

order 3

Reduce [a1, a2, a3] to [[0, 0, 0], ... ,[a1 - 1, a2 - 1, a3 - 1]]

[2, 2, 3].reduce(indicesPermutations, []) // [[0, 0, 0], [0, 0, 1], [0, 0, 2],
                                          //  [0, 1, 0], [0, 1, 1], [0, 1, 2],
                                          //  [1, 0, 0], [1, 0, 1], [1, 0, 2],
                                          //  [1, 1, 0], [1, 1, 1], [1, 1, 2]]

License

MIT