Transform array of objects and concat object values

Question

I have an array of objects I need transformed into an array of new objects. Is there a way this can be done without manually defining "texas" or "california" when defining the new array of objects?

This is my original data:

const data = [
    {
      year: "2005",
      texas: 6.984323232343243
    },
    {
      year: "2006",
      texas: 8.507629970573532
    },
    {
      year: "2005",
      california: 8.422823214889691
    },
    {
      year: "2006",
      california: 9.456857576876532
    }
  ];

And I need it to look like this:

const newData = [
    {
      year: 2005,
      texas: 6.984323232343243,
      california: 8.422823214889691
    },
    {
      year: 2006,
      texas: 8.507629970573532,
      california: 9.456857576876532
    }
  ];

I’ve attempted to group these objects and then ungroup, but I’ve only been able to group and can’t seem to figure out how to ungroup it the way I need. Is there a way I can do this without grouping it first?

const data = [
    {
      year: "2005",
      texas: 6.984323232343243
    },
    {
      year: "2006",
      texas: 8.507629970573532
    },
    {
      year: "2005",
      california: 8.422823214889691
    },
    {
      year: "2006",
      california: 9.456857576876532
    }
  ];
const groupByReduce = (array, key) => {
    return array.reduce((result, currentValue) => {
      (result[currentValue[key]] = result[currentValue[key]] || []).push(
        currentValue
      )
      return result
    }, {});
  };
const newData = groupByReduce(data, "year");

console.log(newData);

.as-console-wrapper { max-height: 100% !important; top: 0; }

const groupedData = groupByReduce(data, 'year')

grigs
– grigs

2020-07-07 17:22:20 +00:00
Commented Jul 7, 2020 at 17:22 — grigs
– grigs, Commented Jul 7, 2020 at 17:22

Sajeeb Ahamed · Accepted Answer · 2020-07-07 17:19:53Z

3

You can use reduce in such way-

const data = [
  {year: "2005", texas: 6.984323232343243},
  {year: "2006", texas: 8.507629970573532},
  {year: "2005", california: 8.422823214889691},
  {year: "2006", california: 9.456857576876532}
];

let res = data.reduce((a, c) => ({...a, [c.year]: {...a[c.year], ...c}}), {});

res = Object.values(res);

console.log(res);

.as-console-wrapper {min-height: 100%!important; top: 0}

answered Jul 7, 2020 at 17:19

Sajeeb Ahamed

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1 Comment

grigs Over a year ago

Wow, this is awesome! I'm still learning how to fully use reduce. This is amazing and does exactly what I need, thank you!

Sajeeb Ahamed · Accepted Answer · 2020-07-07 17:33:18Z

2

Build an object with keys as year and aggregate the values.

const data = [
  {year: "2005", texas: 6.984323232343243},
  {year: "2006", texas: 8.507629970573532},
  {year: "2005", california: 8.422823214889691},
  {year: "2006", california: 9.456857576876532}
];

const convert = (arr, res = {}) => {
  arr.forEach((obj) => (res[obj.year] = { ...(res[obj.year] ?? {}), ...obj }));
  return Object.values(res);
};

console.log(convert(data));

edited Jul 7, 2020 at 17:33

Sajeeb Ahamed

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answered Jul 7, 2020 at 17:24

Siva Kondapi Venkata

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Comments

FZs · Accepted Answer · 2020-07-07 17:33:10Z

0

You can modify your code to use Object.assign to merge objects, and Object.values to discard keys used for grouping:

const data = [
  {year: "2005", texas: 6.984323232343243},
  {year: "2006", texas: 8.507629970573532},
  {year: "2005", california: 8.422823214889691},
  {year: "2006", california: 9.456857576876532}
]

const groupByReduce = (array, key) => {
  return Object.values(array.reduce((result, currentValue) => (
    Object.assign(
      result[currentValue[key]] || (result[currentValue[key]] = {}),
      currentValue
    ),
    result
  ), {}))
}

console.log(groupByReduce(data, 'year'))

answered Jul 7, 2020 at 17:33

FZs

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Comments

3limin4t0r · Accepted Answer · 2020-07-07 17:34:50Z

You can group all objects based upon their year, then merge all objects in a group together.

function groupBy(iterable, fn) {
  const groups = new Map();
  for (const item of iterable) {
    const key = fn(item);
    if (!groups.has(key)) groups.set(key, []);
    groups.get(key).push(item);
  }
  return groups;
}

const data = [
  { year: "2005", texas:      6.984323232343243 },
  { year: "2006", texas:      8.507629970573532 },
  { year: "2005", california: 8.422823214889691 },
  { year: "2006", california: 9.456857576876532 },
];

               // group objects based upon year
const result = Array.from(groupBy(data, obj => obj.year).values())
               // merge all objects in a group together
               .map(values => Object.assign({}, ...values));

console.log(result);

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