diff --git a/snippets/symmetricDifferenceBy.md b/snippets/symmetricDifferenceBy.md new file mode 100644 index 000000000..250eeaa03 --- /dev/null +++ b/snippets/symmetricDifferenceBy.md @@ -0,0 +1,17 @@ +### symmetricDifferenceBy + +Returns the symmetric difference between two arrays, after applying the provided function to each array element of both. + +Create a `Set` by applying `fn` to each array's elements, then use `Array.filter()` on each of them to only keep values not contained in the other. + +```js +const symmetricDifferenceBy = (a, b, fn) => { + const sA = new Set(a.map(v => fn(v))), + sB = new Set(b.map(v => fn(v))); + return [...a.filter(x => !sB.has(fn(x))), ...b.filter(x => !sA.has(fn(x)))]; +}; +``` + +```js +symmetricDifferenceBy([2.1, 1.2], [2.3, 3.4], Math.floor); // [ 1.2, 3.4 ] +``` diff --git a/snippets/symmetricDifferenceWith.md b/snippets/symmetricDifferenceWith.md new file mode 100644 index 000000000..67d081ccd --- /dev/null +++ b/snippets/symmetricDifferenceWith.md @@ -0,0 +1,16 @@ +### symmetricDifferenceWith + +Returns the symmetric difference between two arrays, using a provided function as a comparator. + +Use `Array.filter()` and `Array.findIndex()` to find the appropriate values. + +```js +const symmetricDifferenceWith = (arr, val, comp) => [ + ...arr.filter(a => val.findIndex(b => comp(a, b)) === -1), + ...val.filter(a => arr.findIndex(b => comp(a, b)) === -1), +]; +``` + +```js +symmetricDifferenceWith([1, 1.2, 1.5, 3, 0], [1.9, 3, 0, 3.9], (a, b) => Math.round(a) === Math.round(b)); // [1, 1.2, 3.9] +``` diff --git a/tag_database b/tag_database index 231cf9379..58c4f00fc 100644 --- a/tag_database +++ b/tag_database @@ -200,6 +200,8 @@ sum:math,array sumBy:math,array,function sumPower:math symmetricDifference:array,math +symmetricDifferenceBy:array,function +symmetricDifferenceWith:array,function tail:array take:array takeRight:array