unique

Remove duplicate values.

Alternatives: unique, isUnique.

function unique(x, fc, fm)
// x:  an array
// fc: compare function (a, b)
// fm: map function (v, i, x)

⏱️ Compare function ⇒ O(n²).

const xarray = require('extra-array');

var x = [1, 2, 3, 4, 2, 3];
xarray.unique(x);
// → [ 1, 2, 3, 4 ]

var x = [1, 2, 3, 4, -2, -3];
xarray.unique(x, (a, b) => Math.abs(a) - Math.abs(b));
// → [ 1, 2, 3, 4 ]

xarray.unique(x, null, v => Math.abs(v));
// → [ 1, 2, 3, 4 ]

References

• Data.List.nub() : Haskell
• List-Extra.unique() : Elm
• List-Extra.uniqueBy() : Elm
• _.uniq() : Lodash
• _.uniqBy() : Lodash
• _.uniqWith() : Lodash
• Array.unique() : Sugar.js