30-seconds-of-code/snippets/unzip.md

title, tags, expertise, cover, firstSeen, lastUpdated

title	tags	expertise	cover	firstSeen	lastUpdated
Ungroup array elements	array	intermediate	blog_images/glass-blowing.jpg	2018-01-24T12:35:25+02:00	2020-10-22T20:24:44+03:00

Creates an array of arrays, ungrouping the elements in an array produced by zip.

• Use Math.max(), Function.prototype.apply() to get the longest subarray in the array, Array.prototype.map() to make each element an array.
• Use Array.prototype.reduce() and Array.prototype.forEach() to map grouped values to individual arrays.

const unzip = arr =>
  arr.reduce(
    (acc, val) => (val.forEach((v, i) => acc[i].push(v)), acc),
    Array.from({
      length: Math.max(...arr.map(x => x.length))
    }).map(x => [])
  );

unzip([['a', 1, true], ['b', 2, false]]); // [['a', 'b'], [1, 2], [true, false]]
unzip([['a', 1, true], ['b', 2]]); // [['a', 'b'], [1, 2], [true]]