Sum array values in object of arrays

Question

I'm looking to sum positions in an object of arrays. Essentially, each number represents a yearly amount for an expense line item, and I need to sum these up for each year. The object looks like this (see below) and the result should be an array which = [1500, 1900, 2400] given the object below.

x = [{
      "HVAC": [100, 200, 300, 400],
      "foundation": [500, 600, 700, 800],
      "roof": [900, 1000, 1100, 1200]
    }];

If the arrays weren't named, and instead looked like:

x = [
          [100, 200, 300, 400],
          [500, 600, 700, 800],
          [900, 1000, 1100, 1200]
        ];

Then this function would do what I want (thanks to this post Sum array of arrays (matrix) vertically efficiently/elegantly):

 $scope.reserveTotals = x.reduce(function(a, b) {
      return a.map(function(v, i) {
        return v + b[i];
      });
    });

As it stands, I need to keep the original structure and am just struggling to adapt that function do what I need. Any help appreciated!

Nina Scholz · Accepted Answer · 2016-05-10 16:46:14Z

3

A slightly different solution.

var x = { "HVAC": [100, 200, 300, 400], "foundation": [500, 600, 700, 800], "roof": [900, 1000, 1100, 1200] },
    result = Object.keys(x).reduce(function (r, k) {
        x[k].forEach(function (a, i) {
            r[i] = (r[i] || 0) + a;
        });
        return r;
    }, []);

document.write('<pre>' + JSON.stringify(result, 0, 4) + '</pre>');

answered May 10, 2016 at 16:46

Nina Scholz

388k26 gold badges367 silver badges417 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Nenad Vracar · Accepted Answer · 2016-05-10 16:39:38Z

2

You can use for...in loop and reduce

x = [{
  "HVAC": [100, 200, 300, 400],
  "foundation": [500, 600, 700, 800],
  "roof": [900, 1000, 1100, 1200]
}];

for(var p in x[0]) {
  x[0][p] = x[0][p].reduce((a, b) => { return a + b});
}

console.log(x)

answered May 10, 2016 at 16:39

Nenad Vracar

122k16 gold badges160 silver badges184 bronze badges

Collectives™ on Stack Overflow

Sum array values in object of arrays

2 Answers 2

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related