CODEWITHSUNDEEP
javascript
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Reputation: 116950

Dividing elements in one array by elements in other?

Maybe trivial but what is an elegant way of dividing elements in one array by another (assume arrays are of equal length)? For instance

var A = [2,6,12,18]
var B = [2,3,4,6]

Dividing should give me: [1,2,3,3]

Upvotes: 9

Views: 7290

Answers (4)

Tomalak
Tomalak

Reputation: 338326

If you consider changing the Array prototype an option:

Array.prototype.zip = function (other, reduce, thisArg) {
  var i, result = [], args, 
      isfunc = typeof reduce == "function",
      l = Math.max(this.length, other.length);

  for (i=0; i<l; i++) {
    args = [ this[i], other[i] ];
    result.push( isfunc ? reduce.apply(thisArg, args) : args );
  }
  return result;
}

var A = [2,6,12,18]
var B = [2,3,4,6]
var C = A.zip(B, function (l, r) { return l / r; });
// -> [1, 2, 3, 3]

Upvotes: 2

Manishearth
Manishearth

Reputation: 16198

There isn't any elegant method per se, as in one which avoids a forloop with a neat trick. There are some methods using map() which have already been listed. Those end up using a (longer) forloop, but they're smaller pieces of code. Otherwise, use this:

 var C= new Array(A.length)
 for(i=0;i<A.length;i++){
  C[i]=A[i]/B[i];
 }

Upvotes: 2

otakustay
otakustay

Reputation: 12405

If you have ES5 support, this may be a good option:

var result = A.map(function(n, i) { return n / B[i]; });

Where n in callback represents the iterated number in A and i is the index of n in A.

Upvotes: 27

Waynn Lue
Waynn Lue

Reputation: 11385

Assuming the two arrays are always the same length:

var C = [];
for (var i = 0; i < A.length; i++) {
  C.push(A[i] / B[i]);
}

Upvotes: 3

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