Grouping array object based on values

Question

So I have an array object variable with this structure

var array_obj = [
   {
      Gooble: 240,
      year: 2018
   },
   {
      Koolle: 220,
      year: 2018
   }
    {
      Zooae: 220,
      year: 2015
   }
];

But I want to follow this structure instead https://www.amcharts.com/demos/stacked-column-chart

So now it should be

    var array_obj = [
       {
          Gooble: 240,
          Koolle: 220,
          year: 2018
       },
       {
          Zooae: 220,
          year: 2015
       }
    ];

I've been trying to this with this loop but I can't seem to do it properly.

for(var i in array_obj){
   if(array_obj[i].year == array_obj[i].year){
      # Push here
   }
}

The proposed structure should probably be more like [{ year: 2018, entries: [{ name: 'Zooae', value: 220 }, ...] }, ...] or similar? — Marty
– Marty, Commented Oct 10, 2018 at 2:14
@Marty I'm following this structure from this chart amcharts.com/demos/stacked-column-chart — Jason Rayga
– Jason Rayga, Commented Oct 10, 2018 at 2:31

slider · Accepted Answer · 2018-10-10 02:22:31Z

1

Another solution is to build an object with year as keys and combined data as values:

var array_obj = [{
    Gooble: 240,
    year: 2018
  },
  {
    Koolle: 220,
    year: 2018
  },
  {
    Zooae: 220,
    year: 2015
  }
];

let yearBuckets = {};
array_obj.forEach(b => {
  if (b.year in yearBuckets) Object.assign(yearBuckets[b.year], b);
  else yearBuckets[b.year] = b;
});
console.log(Object.values(yearBuckets));

answered Oct 10, 2018 at 2:22

slider

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Comments

CertainPerformance · Accepted Answer · 2018-10-10 02:12:56Z

1

Use reduce to create an object of objects indexed by year, creating the subobject first if it doesn't exist, and then iterate over the non-year properties and assigning to the appropriate key on the subobject.

Also make sure to correct your input array_obj - all array items need to be separated with commas for the syntax to be valid:

var array_obj = [
   {
      Gooble: 240,
      year: 2018
   },
   {
      Koolle: 220,
      year: 2018
   },
    {
      Zooae: 220,
      year: 2015
   }
];
const outputByYear = array_obj.reduce((a, { year, ...rest }) => {
  if (!a[year]) a[year] = { year };
  Object.entries(rest).forEach(([key, val]) => {
    a[year][key] = val;
  });
  return a;
}, {});
console.log(Object.values(outputByYear));

answered Oct 10, 2018 at 2:12

CertainPerformance

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1 Comment

Jason Rayga Over a year ago

I'll try this. Thank you.

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