Utilize Lodash to group by ID and calculate the sum in order to assign the new sum value

Question

Utilize Lodash to group by ID and calculate the sum in order to assign the new sum value

Is it possible to use Lodash to sort and group by a specific key (such as "id") and update the values of the elements by adding all unique values of another key (e.g. payout)?
For example, can we take the array below:

[
  {
     id: 1,
     payout: 15,
     numOfPeople: 4
  },
  {
     id: 1,
     payout: 12,
     numOfPeople: 3
  },
  {
     id: 2,
     payout: 6,
     numOfPeople: 5
  },
  {
     id: 2,
     payout: 10,
     numOfPeople: 1
  }
]

... and transform it into the following using LODASH:

  // Note how the payout values have been summed up for each id group

[
  {
     id: 1,
     payout: 27,
     numOfPeople: 4
  },
  {
     id: 1,
     payout: 27,
     numOfPeople: 3
  },
  {
     id: 2,
     payout: 16,
     numOfPeople: 5
  },
  {
     id: 2,
     payout: 16,
     numOfPeople: 1
   }
 ]

javascript arrays

Answer 1

Answer №1

To achieve this, you can utilize a combination of filter, map, and reduce.

const data = [
  {
    id: 1,
    payout: 15,
    numOfPeople: 4,
  },
  {
    id: 1,
    payout: 12,
    numOfPeople: 3,
  },
  {
    id: 2,
    payout: 6,
    numOfPeople: 5,
  },
  {
    id: 2,
    payout: 10,
    numOfPeople: 1,
  },
];

const idPayoutMap = {};

let finalResult = data.map(item => {
  if (idPayoutMap['' + item.id] !== undefined) {
    item.payout = idPayoutMap['' + item.id];
  } else {
    item.payout = data
      .filter(elem => elem.id === item.id)
      .reduce((total, elem) => elem.payout + total, 0);
    idPayoutMap['' + item.id] = item.payout;
  }

  return item;
});


console.log(finalResult);

Check out a working demo here

Answer 2

To achieve this, you can utilize a combination of filter, map, and reduce.

const data = [
  {
    id: 1,
    payout: 15,
    numOfPeople: 4,
  },
  {
    id: 1,
    payout: 12,
    numOfPeople: 3,
  },
  {
    id: 2,
    payout: 6,
    numOfPeople: 5,
  },
  {
    id: 2,
    payout: 10,
    numOfPeople: 1,
  },
];

const idPayoutMap = {};

let finalResult = data.map(item => {
  if (idPayoutMap['' + item.id] !== undefined) {
    item.payout = idPayoutMap['' + item.id];
  } else {
    item.payout = data
      .filter(elem => elem.id === item.id)
      .reduce((total, elem) => elem.payout + total, 0);
    idPayoutMap['' + item.id] = item.payout;
  }

  return item;
});


console.log(finalResult);

Check out a working demo here

Utilize Lodash to group by ID and calculate the sum in order to assign the new sum value

Answer №1

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