CODEWITHSUNDEEP
javascriptarrays
NewProgrammer
NewProgrammer

Reputation: 452

How to sum duplicated values inside array in order

I need some help to sum values inside an array in order

I have two arrays:

array1 = ['car', 'car', 'ball', 'piano', 'car'] 
array2 = ['2500', '1000', '400', '2500', '4500']

I'm using this code below to remove the duplicated values inside array1:

var uniqueValues = [];
for(var i in array1){
    if(uniqueValues.indexOf(array1[i]) === -1){
       uniqueValues.push(array1[i]);
    }
}

//returns ['car', 'ball', 'piano']

What I need is to sum the values of array2 using the order of array1, so I will have this result:

result = ['8000', '400', '2500']

So the final result would be this:

array1 = ['car', 'ball', 'piano'] 
array2 = ['8000', '400', '2500']

Any suggestion ? thank you.

Upvotes: 2

Views: 158

Answers (8)

PeterKA
PeterKA

Reputation: 24638

(1) Use Array#reduce() and Object.assign() to build an object with unique keys (and values summed):

{ car: 8000, ball: 400, piano: 2500 }

(2) Use Object.keys() to get new array1:

[ 'car', 'ball', 'piano' ]

(3) Use Object.values() to get new array2:

[ 8000, 400, 2500 ]

DEMO 1

let array1 = ['car', 'car', 'ball', 'piano', 'car'];
let array2 = ['2500', '1000', '400', '2500', '4500'];

const result = array1.reduce((acc, cur, index) => Object.assign(acc, {
    [cur]: (acc[cur] || 0) + +array2[index]
}), {});

array1 = Object.keys(result);
array2 = Object.values(result);

console.log(array1);
console.log(array2);

You can also return an object literal directly in Array#reduce() as follows:

const result = array1.reduce((acc, cur, index) => ({
    ...acc,
    [cur]: ((acc[cur] || 0) + +array2[index])
}), {});

DEMO 2

let array1 = ['car', 'car', 'ball', 'piano', 'car'];
let array2 = ['2500', '1000', '400', '2500', '4500'];

const result = array1.reduce((acc,cur,index) => ({...acc,[cur]:((acc[cur] || 0) + +array2[index])}), {});

array1 = Object.keys(result);
array2 = Object.values(result);

console.log(array1);
console.log(array2);

Upvotes: 2

mplungjan
mplungjan

Reputation: 177975

Reduce will do the trick

NOTE Does JavaScript guarantee object property order?

let array1 = ['car', 'car', 'ball', 'piano', 'car'] 
let array2 = ['2500', '1000', '400', '2500', '4500']

const merged = array1.reduce((acc,cur,i) => {
  acc[cur] = (acc[cur] || 0) + +array2[i]; // add after casting to number
  return acc
},{})

console.log(merged)

array1 = Object.keys(merged)
array2 =  Object.values(merged)

console.log(array1)
console.log(array2)

Upvotes: 3

Nakul Gawande
Nakul Gawande

Reputation: 536

Not exactly the best solution, but should work. I have used the map to create an index and add the values. It is a simple one.

let array1 = ['car', 'car', 'ball', 'piano', 'car', 'ball', 'piano'];
let array2 = ['2500', '1000', '400', '2500', '4500', '2500', '4500'];
const MapOfItems = new Map();
array1.forEach(function(item, index) {
  if (MapOfItems.has(item))
    MapOfItems.set(item, MapOfItems.get(item) + +array2[index]);
  else
    MapOfItems.set(item, +array2[index]);
});

console.log(MapOfItems);
console.log(MapOfItems.keys());
console.log(MapOfItems.values());

Upvotes: 1

Delmontee
Delmontee

Reputation: 2364

array1 = ['car', 'car', 'ball', 'piano', 'car'];
array2 = ['2500', '1000', '400', '2500', '4500'];

///Get unique values

var uniqueValues = [];
for (var i in array1) {
  if (uniqueValues.indexOf(array1[i]) === -1) {
    uniqueValues.push(array1[i]);
  }
}

var uniqueSums = [];

///Cycle through all items in original array

var _ind = 0;
array1.forEach(function(element) {

  //get associated value from second array 

  let _var = parseFloat(array2[_ind]);

  //Add value to total value in sum array

  let _uniqueInd = uniqueValues.indexOf(element);
  if (undefined != uniqueSums[_uniqueInd]) uniqueSums[_uniqueInd] = uniqueSums[_uniqueInd] + _var;
  else uniqueSums[_uniqueInd] = _var;
  _ind++;
});

//override org arrays
array1 = uniqueValues;
array2 = uniqueSums;

console.log(array1);
console.log(array2);

//will result:
//['car', 'ball', 'piano'] 
//['8000', '400', '2500']

Upvotes: 1

David Biderman
David Biderman

Reputation: 198

You can use a for each (this scenario applies if both arrays are same length)

let array1 = ['car', 'car', 'ball', 'piano', 'car'];
let array2 = ['2500', '1000', '400', '2500', '4500'];

const result = {};
array1.forEach((item, i) => {
  if (!result[item]) {
    result[item] = 0;
  }
  result[item] += Number(array2[i])
});

array1 = Object.keys(result); // ['car', 'ball', 'piano']
array2 = Object.values(result); // [8000, 400, 2500]

console.log(array1);
console.log(array2);

Upvotes: 1

Nitheesh
Nitheesh

Reputation: 19986

Please find your issue fixed below.

Logic

  • Create a new array to hold the sum of values called uniqueData.
  • While pushing data to uniqueValues push the value from array2 to uniqueData.
  • If the node already exist, update the sume value.

const array1 = ['car', 'car', 'ball', 'piano', 'car'] 
const array2 = ['2500', '1000', '400', '2500', '4500']

const uniqueValues = [];
const uniqueData = [];
for(var i in array1) {
  const index = uniqueValues.indexOf(array1[i]);
    if(index === -1){
      uniqueValues.push(array1[i]);
      uniqueData.push(array2[i]);
    } else {
      uniqueData[index] = (+uniqueData[index] + +array2[i]).toString()
    }
}

console.log(uniqueValues);
console.log(uniqueData);

Please find Array.reduce implementation of your requirement below. You can find the description as the code comment.

//Your dataset
const array1 = ['car', 'car', 'ball', 'piano', 'car'];
const array2 = ['2500', '1000', '400', '2500', '4500'];

// Array to hold the sum from array2
const uniqueData = [];

// Array to hold the aggrigate of array1
const uniqueValues = array1.reduce((acc, curr, itration) => {
  // acc: accumulator
  // curr: current node
  // itratiion: index of each node from array1

  // if the node is already present in accumulator
  // Dont push it to accumulator
  // Instead update the sume value in uniqueData array
  const index = acc.indexOf(curr);
  if(index === -1) {
    // Node is not there in accumulator
    // Then push to accumulator
    acc.push(curr);
    // Push the value in the index `itration` from `array2` to `uniqueData` array
    uniqueData.push(array2[itration])
  } else {
    // If the node is found update the data in uniqueData array
    // as the numeric sume of the value in that index and the value from array2
    uniqueData[index] = (+uniqueData[index] + +array2[itration]).toString()
  }
  return acc;
}, []); 
console.log(uniqueValues);
console.log(uniqueData);

Upvotes: 2

Invizi
Invizi

Reputation: 1298

Here is how to do it with reduce.

const array1 = ['car', 'car', 'ball', 'piano', 'car']
const array2 = ['2500', '1000', '400', '2500', '4500']

const result = array1.reduce((a, word, index) => {
  if (!a[word]) a[word] = 0;
  a[word] += Number(array2[index]);
  return a
}, {});

const [keys, values] = [
  Object.keys(result),
  Object.values(result)
];

console.log({
  keys
}, {
  values
})

Upvotes: 0

fire
fire

Reputation: 159

You can use a Map: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map

If the number values are Strings like in your example, you also need to cast them to numbers first.

array1 = ['car', 'car', 'ball', 'piano', 'car']
array2 = [2500, 1000, 400, 2500, 4500]

var map = new Map();

for (var i = 0; i < array1.length; i++) {
  var mapval = map.get(array1[i]);
  if (mapval == null) mapval = 0;
  mapval += array2[i];
  map.set(array1[i], mapval)
}

function logMapElements(value, key, map) {
  console.log(`m[${key}] = ${value}`);
}
map.forEach(logMapElements);

Upvotes: 2

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