Is there a method in lodash to map over an array of arrays
I would like to do something like this so that it keeps the structure of the array.
def double(x) { return x*2 }
_([[1,2],[3,4]]).somemethod(double) == [[2,4],[6,8]]
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6 Answers
Just _.map it twice:
var array = [[1, 2], [3, 4]];
var doubledArray = _.map(array, function (nested) {
return _.map(nested, function (element) {
return element * 2;
});
});
Or without lodash:
var doubledArray = array.map(function (nested) {
return nested.map(function (element) {
return element * 2;
});
});
Furthermore, consider using es6 arrow functions:
var doubledArray = array.map(nested => nested.map(element => element * 2));
Comments
You can make your code much cleaner with ES2015 arrow functions:
var array = [[1, 2], [3, 4]];
var double = x => x * 2;
var doubledArray = _.map( array, subarray => _.map( subarray, double ));
Using vanilla JS:
var array = [[1, 2], [3, 4]];
var double = x => x * 2;
var doubledArray = array.map( subarray => subarray.map( double ));
2 Comments
Mike Cluck
Assuming the target environment supports them and/or they transpile it with something like Babel.
andygoestohollywood
arrow functions have nothing to do with his question.
It's much more elegant to use the es6 destructuring syntax within your map statement:
array.map(([ a, b ]) => [ a*2, b*2 ]);
Comments
const deepMap=(input,callback)=>input.map(entry=>entry.map?deepMap(entry,callback):callback(entry))
//test
deepMap([1,2,3,[1,2]],x=>x*2) // [1,4,9,[1,4]]
Comments
The simple way to do that at ES5:
[].concat(...this.array1.map(ap => ap.subArray))
1 Comment
Julian Gonggrijp
I'm failing to see how this answers the question.
It can be a kind of entangle:
var Coef = Array.apply(null, Array(3)).map(function(){return
Array.apply(null, Array(4)).map(function(){return 0})})
Nevertheless, it can be useful if you want to initialize an array in Gas
