diff --git a/snippets/zipWith.md b/snippets/zipWith.md new file mode 100644 index 000000000..e50b9a928 --- /dev/null +++ b/snippets/zipWith.md @@ -0,0 +1,27 @@ +### zipWith + +Creates an array of elements, grouped based on the position in the original arrays and using function as the last value to specify how grouped values should be combined. + +Check if the last argument provided in a function. +Use `Math.max()` to get the longest array in the arguments. +Creates an array with that length as return value and use `Array.from()` with a map-function to create an array of grouped elements. +If lengths of the argument-arrays vary, `undefined` is used where no value could be found. +The function is invoked with the elements of each group `(...group)`. + +``` js +const zipWith = (...arrays) => { + const length = arrays.length; + let fn = length > 1 ? arrays[length - 1] : undefined; + fn = typeof fn == 'function' ? (arrays.pop(), fn) : undefined; + const maxLength = Math.max(...arrays.map(x => x.length)); + const result = Array.from({ length: maxLength }).map((_, i) => { + return Array.from({ length: arrays.length }, (_, k) => arrays[k][i]); + }) + return fn ? result.map(arr => fn(...arr)) : result; +} +``` + +``` js +zipWith([1, 2], [10, 20], [100, 200], (a,b,c) => a + b + c); // [111,222] +zipWith([1, 2, 3], [10, 20], [100, 200], (a,b,c) => (a != null ? a : 'a') + (b != null ? b:'b') + (c != null ? c : 'c')); // [111, 222, '3bc'] +``` diff --git a/tag_database b/tag_database index d1cd81502..6b69c3f7d 100644 --- a/tag_database +++ b/tag_database @@ -216,3 +216,4 @@ words:string,regexp yesNo:utility,regexp zip:array zipObject:array,object +zipWith:array,advanced