Javascript Array of object join duplicates

Question

I need find dublicates by country code and join them into one object

Array structure is:

[{...},{...}]

Objects

{Country_Code: "RU", Country: "Russia", Provider: "Shell1", Price: "0.123"},
{Country_Code: "EN", Country: "Russia", Provider: "Shell", Price: "0.76856"},
{Country_Code: "RO", Country: "Russia", Provider: "Shell", Price: "0.563"},
{Country_Code: "RU", Country: "Russia", Provider: "Shell2", Price: "0.90890"},
{Country_Code: "RU", Country: "Russia", Provider: "Shell3", Price: "0.90"}

I need get Array of object

[{Country_Code: "RU", Country: "Russia", Provider: "Shell1 - 0.123</br>Shell2 - 0.90890</br>Shell3 - 0.90", Price: "0.123"},
{Country_Code: "EN", Country: "Russia", Provider: "Shell", Price: "0.76856"},
{Country_Code: "RO", Country: "Russia", Provider: "Shell", Price: "0.563"}]

If think must be somethink like

var NewArr =[],NewObj ={};
data.forEach(function(dataItem,index) {
    CC = dataItem.Country_Code;
    counts[CC]= (counts[CC]||0) + 1; // Count duplicates
        if(counts[CC]>1){
            NewObj.Country_Code = dataItem.Country_Code;
            NewObj.Country = dataItem.Country;
            NewObj.Provider = dataItem.Provider + " - " + dataItem.Price + "</br>";
            NewObj.Price = dataItem.Price;
            NewArr[indexOfDup] = NewObj; //but how to know index?
        }else{
            NewArr.push(data[index]);
        }

});

But it wrong, so how to write right syntax?

Answer 1

You will need array.reduce . Return a array using array.reduce. In this array check if there already exist an object where the country_code exist using findIndex . If it exist then update the property value

 let x = [{ Country_Code: "RU", Country: "Russia", Provider: "Shell1", Price: "0.123" }, { Country_Code: "EN", Country: "Russia", Provider: "Shell", Price: "0.76856" }, { Country_Code: "RO", Country: "Russia", Provider: "Shell", Price: "0.563" }, { Country_Code: "RU", Country: "Russia", Provider: "Shell2", Price: "0.90890" }, { Country_Code: "RU", Country: "Russia", Provider: "Shell3", Price: "0.90" } ] let m = x.reduce(function(acc, curr) { let findIndex = acc.findIndex((item) => { return item['Country_Code'] === curr['Country_Code'] }); if (findIndex === -1) { acc.push(curr) } else { acc[findIndex].Provider = acc[findIndex].Provider + ' - ' + acc[findIndex].Price + '<br/>' + curr.Provider + ' - ' + curr.Price } return acc; }, []); console.log(m) 

Answer 2

'use strict';

const data = [
  {Country_Code: "RU", Country: "Russia", Provider: "Shell1", Price: "0.123"},
  {Country_Code: "EN", Country: "Russia", Provider: "Shell", Price: "0.76856"},
  {Country_Code: "RO", Country: "Russia", Provider: "Shell", Price: "0.563"},
  {Country_Code: "RU", Country: "Russia", Provider: "Shell2", Price: "0.90890"},
  {Country_Code: "RU", Country: "Russia", Provider: "Shell3", Price: "0.90"}
];

// create a hashmap by country code
const dataPerCountry = data.reduce((dataCountry, currentValue) => {
  const item = {  }
  if (dataCountry[currentValue.Country_Code]) {
    dataCountry[currentValue.Country_Code].Provider.push(currentValue.Provider);
  } else {
    dataCountry[currentValue.Country_Code] = { 
      ...currentValue,
      Provider: [currentValue.Provider],
    };
  }

  return dataCountry;
}, {});

/** 
 * Transform the hasmap into an array of objects used by the view,
 * also applying the transformation to concat the Providers
 **/
const reducedCountriesVO = Object.keys(dataPerCountry).map((countryCode) => {
  const dataCountry = { ...dataPerCountry[countryCode] };

  dataCountry.Provider = dataCountry.Provider.join('<br>-');

  return dataCountry;
});

console.log(reducedCountriesVO);

Answer 3

There are many ways to solve it. Here is my small contribution, the algorithm that I have proposed doesn't use any search algorithm. So, it can perform relative fast for big arrays.

var myArray = [{Country_Code: "RU", Country: "Russia", Provider: "Shell1", Price: "0.123"},
{Country_Code: "EN", Country: "Russia", Provider: "Shell", Price: "0.76856"},
{Country_Code: "RO", Country: "Russia", Provider: "Shell", Price: "0.563"},
{Country_Code: "RU", Country: "Russia", Provider: "Shell2", Price: "0.90890"},
{Country_Code: "RU", Country: "Russia", Provider: "Shell3", Price: "0.90"}];


var groupByCountryCode = function(xs, key) {
  return xs.reduce(function(rv, x) {
    if(rv[x[key]]){
      // It has found more than one instance

      rv[x[key]][0].Provider += " " + x.Provider;
    }else{
      rv[x[key]] = [];
      rv[x[key]].push(x);
    }
    return rv;
  }, {});
};

var grouppedElementsByKey = groupByCountryCode(myArray,"Country_Code");

var grouppedArray =   Object.keys(grouppedElementsByKey).map(function(key){
  return grouppedElementsByKey[key][0];
});


console.log(grouppedArray);

The final output will be like you have requested.

Answer 4

Here is one solution using reduce . First, I created a map structure using arrays for properties that have multiple values. Then I use the organized structure to format the data to look the way you want:

 var data = [{ Country_Code: "RU", Country: "Russia", Provider: "Shell1", Price: "0.123" }, { Country_Code: "EN", Country: "Russia", Provider: "Shell", Price: "0.76856" }, { Country_Code: "RO", Country: "Russia", Provider: "Shell", Price: "0.563" }, { Country_Code: "RU", Country: "Russia", Provider: "Shell2", Price: "0.90890" }, { Country_Code: "RU", Country: "Russia", Provider: "Shell3", Price: "0.90" }]; //First, make a map structure for organization var map = data.reduce((map, el) => { let provider = []; let price = []; if (map[el.Country_Code]) { provider = map[el.Country_Code].Provider; price = map[el.Country_Code].Price; } provider.push(el.Provider); price.push(el.Price); map[el.Country_Code] = { Country_Code: el.Country_Code, Country: el.Country, Provider: provider, Price: price } return map; }, {}); //Use the data map to display the data however you want var formatted = Object.values(map).map((el) => { return { Country_Code: el.Country_Code, Country: el.Country, Provider: el.Provider.reduce((str, providerEl, idx) => { return str += `${providerEl} - ${el.Price[idx]}</br>`; }, ''), Price: el.Price[0] //this doesnt make sense IMO, but will leave it since that's how you asked for the data } }); console.log(Object.values(formatted)); //{Country_Code: "RU", Country: "Russia", Provider: "Shell1 - 0.123</br>Shell2 - 0.90890</br>Shell3 - 0.90", Price: "0.123"} 

Answer 5

您可以在此处使用use array.indexOf(someValue)属性。