Suppose I have an array
var fruits = ["Banana", "Orange", "Lemon", "Apple", "Mango"]
and I have another array of the same size:
var select = [0,1,1,1,0]
How can I get the array fruits[select] = ["Orange", "Lemon", "Apple"], if this makes sense. This is something I can easily do in some other languages (e.g. R), but is this easily doable in JS?
Array.prototype.filter passes its predicate an index, so:
fruits.filter((fruit, i) => select[i])
let fruits = ["Banana", "Orange", "Lemon", "Apple", "Mango"];
let select = [0, 1, 1, 1, 0];
let result = fruits.filter((fruit, i) => select[i]);
console.log(result);Not the way you want to do it. However, something like below should work, granted the syntax might not be exactly correct.
var x = 0;
var selectedFruits = []
foreach(var bit in select)
{
if(bit == 1)
selectedFruits.Add(fruits[x])
x++
}
Another solution could be to shift the values of select for filtering. This mutates select and needs a binding of this array.
var fruits = ["Banana", "Orange", "Lemon", "Apple", "Mango"],
select = [0, 1, 1, 1, 0],
selected = fruits.filter([].shift.bind(select));
console.log(selected);Or just without binding but with thisArg of Array#filter
var fruits = ["Banana", "Orange", "Lemon", "Apple", "Mango"],
select = [0, 1, 1, 1, 0],
selected = fruits.filter([].shift, select);
console.log(selected);
fruits and one for select. no quadratic time.shift() takes time proportional to the size of the array. (V8 optimizes it to not move anything for small arrays, though.)