permutils

Utility package for permutations, including Lehmer codes.

$3

``
var permutils = require('permutils');

/ .swap and .shuffle are useful permutation utilities /
var array = ["a", "b", "c"];
permutils.swap(array, 0, 1); // array is now ["b", "a", "c"]
permutils.shuffle(array); // Fisher–Yates shuffle, array is randomly ordered

/ Use .factoriadic and .unfactoriadic to encode/decode permutations as/from integers /
array = [2, 1, 0];
permutils.factoriadic(array); // -> 5
permutils.unfactoriadic(5, 3); // -> [2, 1, 0]

/ Apply permutations /
array = ["a", "b", "c"];
permutils.permute(array, [0, 1, 2]); // array is untouched
permutils.permute(array, [2, 1, 0]); // array is reversed
`

#### Testing

`
npm run test
npm run test-coverage
``

Currently, permutils has 100% code coverage.