CODEWITHSUNDEEP
javascriptreactjs
Hamza Bouallegue
Hamza Bouallegue

Reputation: 121

how to guet maximum value of object with same name and Id

i have an array of objects like below

   [ 
            {value: 1, id: 1, name: "x"},
            {value: 5, id: 1, name: "x"},
            {value: 1, id: 1, name: "y"},
            {value: 8, id: 1, name: "y"},
            {value: 1, id: 2, name: "x"},
            {value: 3, id: 2, name: "x"},
            {value: 1, id: 2, name: "y"},
            {value: 4, id: 2, name: "y"}
     ]

i want to guet the object with max value with the same "name" and "id" and push it in a new array , the expected output is like this :

   [
     {value: 5, id: 1, name: "x"},
     {value: 8, id: 1, name: "y"},
     {value: 3, id: 2, name: "x"},
     {value: 4, id: 2, name: "y"},
   ]

thank you

Upvotes: 0

Views: 215

Answers (3)

icyKira
icyKira

Reputation: 144

Reduce is used to return a new value that is basically accumulator (adds on previous value) from all the items in the array. Here we can use it to group items using specific key. As you wrote you want to have items showing a record with biggest value having same id and name, these values can be taken as a key (lets look at them as composite private keys of this object).

On each iteration, we check if there is already an object with that key added to the list, if it wasn't we add the object we are now on (during iteration) or if it was already added if its value is smaller than the current object we are on. If the value is smaller, we override the object with the current one.

In the end, we use JS Object.values method that strips away the keys and returns only the values of the object.

const list = [ 
  {value: 1, id: 1, name: "x"},
  {value: 5, id: 1, name: "x"},
  {value: 1, id: 1, name: "y"},
  {value: 8, id: 1, name: "y"},
  {value: 1, id: 2, name: "x"},
  {value: 3, id: 2, name: "x"},
  {value: 1, id: 2, name: "y"},
  {value: 4, id: 2, name: "y"}
 ];

const groupedResults = list.reduce((result, currentObject) => {

  const currentKey = currentObject.id + currentObject.name;

  if (!result[currentKey] || result[currentKey].value <   currentObject.value) { /* Here we check if object with certain key was assigned to previously or if it was is the value smaller than of the object that we are currently seeing */
    result[currentKey] = Object.assign({}, currentObject) //We need to do copy of the object (it can be also done using object destructuring) in order to have a new object that will not be bound by reference with the original one
  };

  return result;
}, {});

const requestedList = Object.values(groupedResults);
console.log(requestedList)

Upvotes: 0

Derek Wang
Derek Wang

Reputation: 10194

Using Array.prototype.reduce, you can group that array using id_name key pair and store the maximum values as follows.

const input = [
  {value: 1, id: 1, name: "x"},
  {value: 5, id: 1, name: "x"},
  {value: 1, id: 1, name: "y"},
  {value: 8, id: 1, name: "y"},
  {value: 1, id: 2, name: "x"},
  {value: 3, id: 2, name: "x"},
  {value: 1, id: 2, name: "y"},
  {value: 4, id: 2, name: "y"}
];

const groupBy = input.reduce((acc, cur) => {
  const key = `${cur.id}_${cur.name}`;
  if (!acc[key]) {
    acc[key] = cur;
  }
  if (acc[key].value < cur.value) {
    acc[key].value = cur.value;
  }
  return acc;
}, {});

const output = Object.values(groupBy);
console.log(output);

Upvotes: 1

Md Sabbir Alam
Md Sabbir Alam

Reputation: 5054

You can use reduce method to do this,

const data = [ 
            {value: 1, id: 1, name: "x"},
            {value: 5, id: 1, name: "x"},
            {value: 1, id: 1, name: "y"},
            {value: 8, id: 1, name: "y"},
            {value: 1, id: 2, name: "x"},
            {value: 3, id: 2, name: "x"},
            {value: 1, id: 2, name: "y"},
            {value: 4, id: 2, name: "y"}
     ]

const res = data.reduce((prev, curr) => {
   const index = prev.findIndex((item) => item.id === curr.id && item.name === curr.name);
   if(index > -1) {
      const obj = prev[index];
      if(obj.value < curr.value) {
          prev[index] = {...obj, value: curr.value};
          return prev;
      }
   }
   prev.push(curr);
   return prev;
}, []);
console.log(res);

Upvotes: 1

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