Reduce array of nested object by value of external object

Question

I have an array as follow:

  const myArray = [
    {
      name: 'banana',
      quotas: [
        {
          title: 'innerBanana1',
          percent: 0.3
        },
        {
          title: 'innerBanana2',
          percent: 0.4
        }
      ]
    },
    {
      name: 'apple',
      quotas: [
        {
          title: 'innerApple1',
          percent: 0.6
        },
        {
          title: 'innerApple2',
          percent: 0.2
        }
      ]
    }
  ]

I would like to sum all the percent in the quotas array only if they belong to the same external object (aka: the name is the same).

Expected Result

finalArray = [
  { name: 'banana', percent: 0.7 },
  { name: 'apple', percent: 0.8 }
]

I tried

  const sum = quotaGroups
    .map(quotaGroup => quotaGroup.quotas)
    .reduce((accumulator, groupedQuota) => {
      return accumulator + groupedQuota[0].percent
    })

But it clearly does not work. I am missing the link on how to sum only the quotas of the inner object if the name is the same

Luke Storry · Accepted Answer · 2020-07-26 14:28:42Z

1

You needed to do the reduce inside the map, otherwise the names were getting lost, and the accumulator was trying to concatenate strings, not total up a number.

const myArray = [
  {
    name: 'banana',
    quotas: [{title: 'innerBanana1', percent: 0.3}, {title: 'innerBanana2', percent: 0.4}]
  }, 
  {
    name: 'apple',
    quotas: [{title: 'innerApple1', percent: 0.6}, {title: 'innerApple2', percent: 0.2}]
  }
]

const sum = myArray
  .map(quotaGroup => ({
    name: quotaGroup.name,
    percent: quotaGroup.quotas.reduce((acc, item) => acc + item.percent, 0)
  }))

console.log(sum)

edited Jul 26, 2020 at 14:28

answered Jul 26, 2020 at 11:51

Luke Storry

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Comments

Siva Kondapi Venkata · Accepted Answer · 2020-07-26 11:52:40Z

1

Use map and reduce

const sum = (arr) =>
  arr.map(({ quotas, name }) => ({
    name,
    percent: quotas.reduce((sum, { percent }) => sum + percent, 0),
  }));
  
const myArray = [
  {
    name: "banana",
    quotas: [
      {
        title: "innerBanana1",
        percent: 0.3,
      },
      {
        title: "innerBanana2",
        percent: 0.4,
      },
    ],
  },
  {
    name: "apple",
    quotas: [
      {
        title: "innerApple1",
        percent: 0.6,
      },
      {
        title: "innerApple2",
        percent: 0.2,
      },
    ],
  },
];



console.log(sum(myArray));

answered Jul 26, 2020 at 11:52

Siva Kondapi Venkata

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Comments

8HoLoN · Accepted Answer · 2020-07-26 11:59:07Z

0

Here is what you want:

const myArray = [
    {
        name: 'banana',
        quotas: [
            {
                title: 'innerBanana1',
                percent: 0.3
            },
            {
                title: 'innerBanana2',
                percent: 0.4
            }
        ]
    },
    {
        name: 'apple',
        quotas: [
            {
                title: 'innerApple1',
                percent: 0.6
            },
            {
                title: 'innerApple2',
                percent: 0.2
            }
        ]
    }
];

console.log(myArray.map(({ name, quotas }) => {
    return { name, percent: quotas.reduce((a, { percent }) => a + percent, 0) }
}));

edited Jul 26, 2020 at 11:59

answered Jul 26, 2020 at 11:52

8HoLoN

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Comments

Jasur · Accepted Answer · 2020-07-26 12:08:41Z

0

let finalArray  = myArray.map(item => {
    let  percent = 0;
    item.quotas.forEach(function (obj) {
        percent += obj.percent
    });
    return {
        name: item.name,
        percent: percent
    }
})

answered Jul 26, 2020 at 12:08

Jasur

112 bronze badges

1 Comment

Mark Rotteveel Over a year ago

Please don't post only code as answer, but also provide an explanation what your code does and how it solves the problem of the question. Answers with an explanation are usually more helpful and of better quality, and are more likely to attract upvotes.

Prathap Reddy · Accepted Answer · 2020-07-26 14:22:52Z

0

Use combination of map and reduce as below

const finalArray = myArray.map(item => ({
  name: item.name,
  percent: item.quotas.reduce((acc, cur) => acc + cur.percent, 0)
}));

edited Jul 26, 2020 at 14:22

answered Jul 26, 2020 at 11:55

Prathap Reddy

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1 Comment

Dave Hogan Over a year ago

Please don't post only code as answer, but also provide an explanation what your code does and how it solves the problem of the question. Answers with an explanation are usually more helpful and of better quality, and are more likely to attract up-votes.

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