Determine the frequency of duplicate elements in an array and arrange them in descending order based on their frequency

Question

Determine the frequency of duplicate elements in an array and arrange them in descending order based on their frequency

After making an API call, my array is populated with values like this:

["9777", "9777", "2.4", "9777", "2.4", "2.4", "9777", "2.4", "2.4", "9777", "9777", "2.4", "2.4", "2.4"]

My goal is to count the occurrences of each item in the array and then sort them in descending order based on the count.

I found a solution on stackoverflow which suggests the following code:

data.forEach(function (x) {
  counts[x] = (counts[x] || 0) + 1;
});

While this code works, it produces strange results that make it challenging to extract the desired values. Here is an example of the results obtained: https://i.sstatic.net/bKVwT.jpg

javascript arrays typescript

Answer 1

Answer №1

An alternative approach involves utilizing the reduce function to tally and construct an object containing the counts, followed by using the sort function.

If there is a need to single out a specific object based on its "name", the find function can be employed:

let array = ["9777", "9777", "2.4", "9777", "2.4", "2.4", "9777", "2.4", "2.4", "9777", "9777", "2.4", "2.4", "2.4"],
    counts = Object.values(array.reduce((a, c) => {
      (a[c] || (a[c] = {name: c, count: 0})).count += 1;
      return a;
    }, {})).sort(({count: ac}, {count: bc}) => bc - ac),
    target = "2.4",
    found = counts.find(({name}) => name === target);

console.log(counts);
console.log(found);
console.log(found.count);

.as-console-wrapper { max-height: 100% !important; top: 0; }

Answer 2

An alternative approach involves utilizing the reduce function to tally and construct an object containing the counts, followed by using the sort function.

If there is a need to single out a specific object based on its "name", the find function can be employed:

let array = ["9777", "9777", "2.4", "9777", "2.4", "2.4", "9777", "2.4", "2.4", "9777", "9777", "2.4", "2.4", "2.4"],
    counts = Object.values(array.reduce((a, c) => {
      (a[c] || (a[c] = {name: c, count: 0})).count += 1;
      return a;
    }, {})).sort(({count: ac}, {count: bc}) => bc - ac),
    target = "2.4",
    found = counts.find(({name}) => name === target);

console.log(counts);
console.log(found);
console.log(found.count);

.as-console-wrapper { max-height: 100% !important; top: 0; }

Answer 3

Answer №2

To begin, start by compiling a distinct list of items and then iterate through this list to append them to the final outcome.

Once the list has been generated, organize it by utilizing the count key that was established during the previous step.

const items = ["9777", "9777", "2.4", "9777", "2.4", "2.4", "9777", "2.4", "2.4", "9777", "9777", "2.4", "2.4", "2.4"];

// Declaring a variable to store the results
const result = [];

// Create a unique list of items to iterate over
// Append each item to the result list
[...new Set(items)].forEach(item => result.push({
  key: item,
  // Calculate the number of occurrences of the current item
  count: items.filter(i => i == item).length
}));

// Sort the array in descending order of item occurrence
result.sort((a, b) => b.count - a.count);

console.log(result);

Answer 4

To begin, start by compiling a distinct list of items and then iterate through this list to append them to the final outcome.

Once the list has been generated, organize it by utilizing the count key that was established during the previous step.

const items = ["9777", "9777", "2.4", "9777", "2.4", "2.4", "9777", "2.4", "2.4", "9777", "9777", "2.4", "2.4", "2.4"];

// Declaring a variable to store the results
const result = [];

// Create a unique list of items to iterate over
// Append each item to the result list
[...new Set(items)].forEach(item => result.push({
  key: item,
  // Calculate the number of occurrences of the current item
  count: items.filter(i => i == item).length
}));

// Sort the array in descending order of item occurrence
result.sort((a, b) => b.count - a.count);

console.log(result);

Determine the frequency of duplicate elements in an array and arrange them in descending order based on their frequency

Answer №1

Answer №2

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