A method of enumerating the elements of an array and arranging them in descending order

Question

A method of enumerating the elements of an array and arranging them in descending order

Collection:

5, 5, 5, 9, 4, 2, 2, 2, 2, 2, 3, 3, 3, 3

Desired Result:

2, 3, 5, 9, 4

Using array_count_values() and arsort() in PHP makes achieving this easy, but I'm facing challenges with implementing it in JavaScript. Any suggestions?

Additionally, is there a way to return the counts along with the elements for potential future requirements?

javascript arrays sorting

Answer 1

Answer №1

Identify distinct entries, form an array of distinct values, then arrange them based on frequency

function count(arr) { // calculate occurrences
    var obj = {}, index;
    for (index = 0; index < arr.length; ++index) {
        if (obj[arr[index]]) ++obj[arr[index]];
        else obj[arr[index]] = 1;
    }
    return obj;
}

function sortArray(arr_input) { // distinct values sorted by frequency
    var obj = count(arr_input),
        finalArr = [], index;
    for (index in obj) finalArr.push(+index); // quickly obtain distinct only
    finalArr.sort(function (a, b) {
        return obj[a] < obj[b];
    });
    return finalArr;
}

sortArray([1, 3, 3, 5, 5, 5, 2, 2, 2, 2]);
// one 1, two 3s, three 5s, four 2s
// [2, 5, 3, 1]

Your example includes both a 9 and a 4, so if you require a specific order, further adjustments would be needed. Otherwise;

sortArray([5, 5, 5, 9, 4, 2, 2, 2, 2, 2, 3, 3, 3, 3]);
// [2, 3, 5, 4, 9]

To generate an Array of Objects

function sortArray(arr_input) { // distinct values sorted by frequency
    var obj = count(arr_input),
        finalArr = [], index;
    for (index in obj) finalArr.push({value: +index, weight: obj[index]}); // quickly get distinct values only
    finalArr.sort(function (a, b) {
        return a.weight < b.weight;
    });
    return finalArr;
}

var result = sortArray([5, 5, 5, 9, 4, 2, 2, 2, 2, 2, 3, 3, 3, 3]);
/* [
    {"value": 2, "weight": 5},
    {"value": 3, "weight": 4},
    {"value": 5, "weight": 3},
    {"value": 4, "weight": 1},
    {"value": 9, "weight": 1}
] */

Now, to access the value at position i, use result[i].value, and for its weightage result[i].weight.

Answer 2

Identify distinct entries, form an array of distinct values, then arrange them based on frequency

function count(arr) { // calculate occurrences
    var obj = {}, index;
    for (index = 0; index < arr.length; ++index) {
        if (obj[arr[index]]) ++obj[arr[index]];
        else obj[arr[index]] = 1;
    }
    return obj;
}

function sortArray(arr_input) { // distinct values sorted by frequency
    var obj = count(arr_input),
        finalArr = [], index;
    for (index in obj) finalArr.push(+index); // quickly obtain distinct only
    finalArr.sort(function (a, b) {
        return obj[a] < obj[b];
    });
    return finalArr;
}

sortArray([1, 3, 3, 5, 5, 5, 2, 2, 2, 2]);
// one 1, two 3s, three 5s, four 2s
// [2, 5, 3, 1]

Your example includes both a 9 and a 4, so if you require a specific order, further adjustments would be needed. Otherwise;

sortArray([5, 5, 5, 9, 4, 2, 2, 2, 2, 2, 3, 3, 3, 3]);
// [2, 3, 5, 4, 9]

To generate an Array of Objects

function sortArray(arr_input) { // distinct values sorted by frequency
    var obj = count(arr_input),
        finalArr = [], index;
    for (index in obj) finalArr.push({value: +index, weight: obj[index]}); // quickly get distinct values only
    finalArr.sort(function (a, b) {
        return a.weight < b.weight;
    });
    return finalArr;
}

var result = sortArray([5, 5, 5, 9, 4, 2, 2, 2, 2, 2, 3, 3, 3, 3]);
/* [
    {"value": 2, "weight": 5},
    {"value": 3, "weight": 4},
    {"value": 5, "weight": 3},
    {"value": 4, "weight": 1},
    {"value": 9, "weight": 1}
] */

Now, to access the value at position i, use result[i].value, and for its weightage result[i].weight.

A method of enumerating the elements of an array and arranging them in descending order

Answer №1

Similar questions

Exploring Bootstrap datatables to search through nested table data with Codeigniter

The equivalent of e.preventDefault() in Java (for Android) is to replace the typed text

After ReactDOM is used, the JavaScript code is no longer functioning properly

Which file should I include: npm-shrinkwrap.json, package-lock.json, or yarn.lock?

Understanding the performance of video in threejs when using getImageData

"Fixing issue with Checkbox not getting checked using a combination of jQuery and

Extract the element when the mouse is clicked

JavaScript - Problem transferring an object between two different JavaScript files

AngularJS Datepicker displaying incorrect dates

Updating a Vue component following an axios POST request

Issue with mouseover functionality not functioning properly while hovering over a dropdown menu

If the element does not already exist, use jQuery to append it; otherwise, replace the existing element

I'm puzzled as to why my Vuex modules are not functioning properly. I keep receiving the error message: "[vuex]

In the Controller, the `getContent` function is configured to display only the token

Testing Vue with Jest - Unable to test the window.scrollTo function

Challenges with downloading a file synchronously using NodeJS

Creating a Custom FlatList Content Container with React Native

Retrieve the value stored within an array object

Searching for empty array fields in a jsonb column using a PostgreSQL query

Updating MongoDB nested item by dynamic ID is a breeze