Locate identical items within an array of objects by comparing their value properties, then merge these duplicates by appending the duplicate object to its label property through array reduction

Question

Locate identical items within an array of objects by comparing their value properties, then merge these duplicates by appending the duplicate object to its label property through array reduction

Let's imagine I have an array of objects structured like the following:

[ 
    {value: "2021", label: "REDS"},
    {value: "2020", label: "REDS"},
    {value: "2021", label: "COPASA"},
    {value: "2021", label: "CEMIG_CLIENTES"},
    {value: "2016", label: "CEMIG_CLIENTES"},
    {value: "2016", label: "RFQSA"}
]

The task at hand is to identify duplicate entries based on the value property and create a new array that combines their label properties. The desired output should look like this:

[ 
    {value: "2021", label: "REDS/COPASA/CEMIG_CLIENTES"},
    {value: "2020", label: "REDS"},
    {value: "2016", label: "CEMIG_CLIENTES/RFQSA"}
]

How can I go about achieving this? I'm currently stuck in my attempts. I've tried extracting unique values using the following code snippet:

 const unique =  arr.map(e => e['value'])
             .map((e, i, final) => final.indexOf(e) === i && i)
             .filter(obj=> aux2[obj])
             .map(e => aux2[e]);

However, this approach falls short as it overlooks the preservation of labels. Another idea I had was to sort the array and devise a method to pinpoint duplicate positions so they can be merged accordingly. But so far, I haven't been successful in implementing it. Is there perhaps a more effective solution out there? If not, could someone offer guidance on how to tackle this challenge?

Thank you for your help in advance!

javascript arrays object

Answer 1

Answer №1

To achieve this, utilize a for loop to iterate through the objects, create a new array, and check if the value already exists. If it does, concatenate the label to the existing entry; otherwise, add a new one:

function removeDuplicateValues(arr) {
  const newArray = [];

  for (const object of arr) {
    const foundValue = newArray.find((element) => element.value === object.value);
    if (foundValue) {
      foundValue.label += "/" + object.label;
    } else {
      newArray.push(object);
    }
  }
  
  return newArray;
}

console.log(removeDuplicateValues([ 
  {value: "2021", label: "REDS"},
  {value: "2020", label: "REDS"},
  {value: "2021", label: "COPASA"},
  {value: "2021", label: "CEMIG_CLIENTES"},
  {value: "2016", label: "CEMIG_CLIENTES"},
  {value: "2016", label: "RFQSA"}
]));

If optimizing performance is crucial, consider using an object as the newArray with the value as the key. This way, you can avoid performing a .find operation in each iteration.

Answer 2

To achieve this, utilize a for loop to iterate through the objects, create a new array, and check if the value already exists. If it does, concatenate the label to the existing entry; otherwise, add a new one:

function removeDuplicateValues(arr) {
  const newArray = [];

  for (const object of arr) {
    const foundValue = newArray.find((element) => element.value === object.value);
    if (foundValue) {
      foundValue.label += "/" + object.label;
    } else {
      newArray.push(object);
    }
  }
  
  return newArray;
}

console.log(removeDuplicateValues([ 
  {value: "2021", label: "REDS"},
  {value: "2020", label: "REDS"},
  {value: "2021", label: "COPASA"},
  {value: "2021", label: "CEMIG_CLIENTES"},
  {value: "2016", label: "CEMIG_CLIENTES"},
  {value: "2016", label: "RFQSA"}
]));

If optimizing performance is crucial, consider using an object as the newArray with the value as the key. This way, you can avoid performing a .find operation in each iteration.

Answer 3

Answer №2

function mergeSimilarItems (arr) {
    const map = {};
    arr.forEach(item => {
        if (!map[item.name]) {
            map[item.name] = item;
        }
        else {
            map[item.name].quantity += item.quantity;
        }
    });

    return Object.values(map);
}

console.log(mergeSimilarItems([ 
    {name: "Apple", quantity: 3},
    {name: "Banana", quantity: 5},
    {name: "Apple", quantity: 2},
    {name: "Orange", quantity: 4}
]))

Answer 4

function mergeSimilarItems (arr) {
    const map = {};
    arr.forEach(item => {
        if (!map[item.name]) {
            map[item.name] = item;
        }
        else {
            map[item.name].quantity += item.quantity;
        }
    });

    return Object.values(map);
}

console.log(mergeSimilarItems([ 
    {name: "Apple", quantity: 3},
    {name: "Banana", quantity: 5},
    {name: "Apple", quantity: 2},
    {name: "Orange", quantity: 4}
]))

Answer 5

Answer №3

If you are in need of a solution, check out this universal method inspired by the response from Giorgi Moniava. I have condensed the code and added the option to choose your own key for identifying duplicates, along with a callback function to determine how values should be combined. In my scenario, I prefer to concatenate duplicate values using a pipe delimiter (refer to usage below).

function mergeDuplicates(array, duplicateKey, combineFunction) {
    return Object.values(
        array.reduce((accumulator, item) => {
            const id = item[duplicateKey];
            accumulator[id] = accumulator[id] ? combineFunction(accumulator[id], item) : item;

            return accumulator;
        }, {})
    );
}

example

mergeSimilar(myArray, "duplicateKey", (main, duplicate) => {
            
    return {
        ...main,
        value: [main.value, duplicate.value].join("|") 
    };
});

Answer 6

If you are in need of a solution, check out this universal method inspired by the response from Giorgi Moniava. I have condensed the code and added the option to choose your own key for identifying duplicates, along with a callback function to determine how values should be combined. In my scenario, I prefer to concatenate duplicate values using a pipe delimiter (refer to usage below).

function mergeDuplicates(array, duplicateKey, combineFunction) {
    return Object.values(
        array.reduce((accumulator, item) => {
            const id = item[duplicateKey];
            accumulator[id] = accumulator[id] ? combineFunction(accumulator[id], item) : item;

            return accumulator;
        }, {})
    );
}

example

mergeSimilar(myArray, "duplicateKey", (main, duplicate) => {
            
    return {
        ...main,
        value: [main.value, duplicate.value].join("|") 
    };
});

Locate identical items within an array of objects by comparing their value properties, then merge these duplicates by appending the duplicate object to its label property through array reduction

Answer №1

Answer №2

Answer №3

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