In javascript, need to perform sum of dynamic array

Question

I have a dynamic array and I need to perform a sum of it.

 {ClientName: "A", Alex: 2, Da: 0, Cal: 0}
{ClientName: "b", Alex: 0, Da: 0, Cal: 4}
{ClientName: "c", Alex: 1, Da: 0, Cal: 5}
{ClientName: "d", Alex: 2, Da: 0, Cal: 0}

in this array, client name is fixed but other columns like Alex, Da, Cal are dynamic and will vary. i need to create a generic function in typescript where output will be like this.

{ClientName: "Total", Alex: 5, Da: 0, Cal: 9}

“Columns are dynamic” means the property names are arbitrary and could be anything? Or is there a certain set of possible column names? — deceze
– deceze ♦, Commented Jan 4, 2019 at 12:57

Rajesh Dixit · Accepted Answer · 2019-01-04 12:58:52Z

3

You can try something like this:

Idea:

Uses Object.keys to get all enumerable keys.
Loop over them ans set them to default if not found. Then add current object's value.
Since you need hardcoded value for ClientName, you can set it either in loop or set it after loop.

const data = [
  {ClientName: "A", Alex: 2, Da: 0, Cal: 0},
  {ClientName: "b", Alex: 0, Da: 0, Cal: 4},
  {ClientName: "c", Alex: 1, Da: 0, Cal: 5},
  {ClientName: "d", Alex: 2, Da: 0, Cal: 0},
]

const output = data.reduce((acc, item) => {
  Object
  .keys(item)
  .forEach((key) => {
    acc[key] = (acc[key] || 0) + item[key]
  });
  acc.ClientName = 'Total'
  return acc;
}, {})

console.log(output)

answered Jan 4, 2019 at 12:58

Rajesh Dixit

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Comments

Nina Scholz · Accepted Answer · 2019-01-04 13:13:07Z

2

You could reduce the wanted values.

var data = [{ ClientName: "A", Alex: 2, Da: 0, Cal: 0 }, { ClientName: "b", Alex: 0, Da: 0, Cal: 4 }, { ClientName: "c", Alex: 1, Da: 0, Cal: 5 }, { ClientName: "d", Alex: 2, Da: 0, Cal: 0 }],
    total = data.reduce((a, { ClientName, ...b }) => Object.assign(
        {},
        a,
        { ClientName: 'total' },
        ...Object.entries(b).map(([k, v]) => ({ [k]: (a[k] || 0) + v }))
    ));
    
console.log(total);

answered Jan 4, 2019 at 13:13

Nina Scholz

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Comments

Dennis Ruiter · Accepted Answer · 2019-01-04 12:59:04Z

0

Something along these lines should work as long as all keys besides ClientName are defined as numbers

arr.reduce((sumObject, item) => {
  Object.keys(item).forEach(key => {
    if(key === 'ClientName'){
      return false
    }

    if(!sumObject[key]) {
      sumObject[key] = item[key]
    } else {
      sumObject[key] += item[key]
    }
  })

   return sumObject
}, {ClientName: 'Total'})

answered Jan 4, 2019 at 12:59

Dennis Ruiter

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Rohit.007 · Accepted Answer · 2019-01-04 13:29:36Z

0

You can iterate with reduce to generate single output and to merge the key count you can use Object.keys and map will allow you to iterate over your object keys. Also added one dynamic key Abc: 9 just to verify the result.

const object = [{
    ClientName: "A",
    Alex: 2,
    Da: 0,
    Cal: 0
  },
  {
    ClientName: "b",
    Alex: 0,
    Da: 0,
    Cal: 4
  },
  {
    ClientName: "c",
    Alex: 1,
    Da: 0,
    Cal: 5
  },
  {
    ClientName: "d",
    Alex: 2,
    Da: 0,
    Cal: 0,
    Abc: 9
  },
]

const result = object.reduce((accumulator, currentValue) => {
  Object.keys(currentValue).map((indexKey) => {
    accumulator[indexKey] = (accumulator[indexKey] || 0) + currentValue[indexKey]
  });
  accumulator.ClientName = "Total";
  return accumulator;
})

console.log(result);

answered Jan 4, 2019 at 13:29

Rohit.007

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3 Comments

Rajesh Dixit Over a year ago

Your solution is exactly same as mine. Please check other answers before posting

Rohit.007 Over a year ago

Yes I do agree, but It seems similar but not exactly, See in you code there is forEach which is less optimized than .map which is being used in my solution. Anyways I have already voted up for your solution.

Rajesh Dixit Over a year ago

using a map without return statement is so much worse. Also i don't think map is more optimised compared to forEach but that discussion can be done later

Loghi Perinpanayagam · Accepted Answer · 2019-01-04 13:07:17Z

-1

 let arr = [
    {ClientName: "A", Alex: 2, Da: 0, Cal: 0},
    {ClientName: "b", Alex: 0, Da: 0, Cal: 4},
    {ClientName: "c", Alex: 1, Da: 0, Cal: 5},
    {ClientName: "d", Alex: 2, Da: 0, Cal: 0}
];

let output = arr.reduce((curr, next) => {
   return {ClientName: "Total", Alex: (curr.Alex + next.Alex ), Da: (curr.Da + next.Da), Cal: (curr.Cal + next.Cal)};
});

console.log(output);

Check this can get the answer simply

answered Jan 4, 2019 at 13:07

Loghi Perinpanayagam

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2 Comments

Rajesh Dixit Over a year ago

OP is looking for a solutions that handles Dynamic columns

Loghi Perinpanayagam Over a year ago

yes you are right , it shoud not work for dynamic columns.thank you,

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