Bucket Sort Visualization Using Javascript

Last Updated : 19 Dec, 2021

GUI(Graphical User Interface) helps in better in understanding than programs. In this article, we will visualize Bucket Sort using JavaScript. We will see how the elements are stored into Buckets and then how Buckets get traversed to get the final sorted array. We will also visualize the time complexity of Bucket Sort.

Refer:

Approach:

First, we will generate a random array using Math.random() function.
Different color is used to indicate which element is being traversed.
Each traversed element is thrown into suitable Bucket.
These buckets are sorted using Insertion Sort.
Further, these buckets are traversed to get the final sorted array.
Since the algorithm performs the operation very fast, the setTimeout() function has been used to slow down the process.
New array can be generated by pressing the “Ctrl+R” key.
The sorting is performed using BucketSort() function using Buckets.

Example:

Before Sorting

After Sorting

Below is the program to visualize the Bucket Sort algorithm.

index.html


<!DOCTYPE html>
<html lang="en">

<head>
    <link rel="stylesheet" href="style.css" />
</head>

<body>
    <br />
    <p class="header">Bucket Sort</p>

    <div id="array"></div>
    <br />
    <br />

    <div style="display: flex; justify-content: space-evenly">
        <div class="bucket">
            <div id="one" class="bucket2"></div>
            <br />
            <h3 style="text-align: center">[1-5]</h3>
        </div>

        <div class="bucket">
            <div id="two" class="bucket2"></div>
            <br />
            <h3 style="text-align: center">[6-10]</h3>
        </div>

        <div class="bucket">
            <div id="three" class="bucket2"></div>
            <br />
            <h3 style="text-align: center">[11-15]</h3>
        </div>
        
        <div class="bucket">
            <div id="four" class="bucket2"></div>
            <br />
            <h3 style="text-align: center">[16-20]</h3>
        </div>
    </div>

    <script src="script.js"></script>
</body>

</html>

style.css: The following is the content for “style.css” used in the above file.

style.css

* {
  margin: 0px;
  padding: 0px;
  box-sizing: border-box;
}
.header {
  font-size: 20px;
  text-align: center;
}
#array {
  background-color: white;
  height: 265px;
  width: 598px;
  margin: auto;
  position: relative;
  margin-top: 64px;
}
.block {
  width: 28px;
  background-color: #6b5b95;
  position: absolute;
  bottom: 0px;
  transition: 0.2s all ease;
}
.block_id {
  position: absolute;
  color: black;
  margin-top: -20px;
  width: 100%;
  text-align: center;
}
.block_id2 {
  position: absolute;
  color: black;
  margin-top: 22px;
  width: 100%;
  text-align: center;
}
.block_id3 {
  position: absolute;
  color: black;
  margin-top: 1px;
  width: 100%;
  text-align: center;
}
.bucket {
  width: 256px;
  height: 260px;
  position: relative;
}
.bucket2 {
  margin: auto;
  width: 148px;
  height: 260px;
}
.firstbucket {
  width: 28px;
  background-color: #6b5b95;
  position: absolute;
  bottom: 0px;
  transition: 0.2s all ease;
}
.secondbucket {
  width: 28px;
  background-color: #6b5b95;
  position: absolute;
  bottom: 0px;
  transition: 0.2s all ease;
}
.thirdbucket {
  width: 28px;
  background-color: #6b5b95;
  position: absolute;
  bottom: 0px;
  transition: 0.2s all ease;
}
.fourthbucket {
  width: 28px;
  background-color: #6b5b95;
  position: absolute;
  bottom: 0px;
  transition: 0.2s all ease;
}

script.js: The following is the content for “script.js” file used in the above HTML code.

script.js


var container = document.getElementById("array");

// Function to randomly shuffle the array
function shuffle(arr) {
  for (var i = arr.length - 1; i > 0; i--) {

    // Generate random number
    var j = Math.floor(Math.random() * (i + 1));
    var temp = arr[i];
    arr[i] = arr[j];
    arr[j] = temp;
  }
}

function generatearray() {

  // Creating an array
  var arr = [];

  // Filling array with values from 1 to 20
  for (var i = 0; i < 20; i++) {
    arr.push(i + 1);
  }

  // Shuffling the array
  shuffle(arr);
  for (var i = 0; i < 20; i++) {
    var value = arr[i];

    // Creating element div
    var array_ele = document.createElement("div");

    // Adding class 'block' to div
    array_ele.classList.add("block");

    // Adding style to div
    array_ele.style.height = `${value * 13}px`;
    array_ele.style.transform = `translate(${i * 30}px)`;

    // Creating label element for displaying
    // size of particular block
    var array_ele_label = document.createElement("label");
    array_ele_label.classList.add("block_id");
    array_ele_label.innerText = value;

    // Appending created elements to index.html
    array_ele.appendChild(array_ele_label);
    container.appendChild(array_ele);
  }
}

async function InsertionSort(clsnam, delay = 600) {
  let blocks = document.getElementsByClassName(clsnam);
  blocks[0].style.backgroundColor = "rgb(49, 226, 13)";

  for (var i = 1; i < blocks.length; i += 1) {
    var j = i - 1;

    // To store the integer value of ith block to key
    var key = parseInt(blocks[i].childNodes[0].innerHTML);

    // To store the ith block height to height
    var height = blocks[i].style.height;

    // Provide darkblue color to the ith block
    blocks[i].style.backgroundColor = "darkblue";

    // To pause the execution of code for 600 milliseconds
    await new Promise((resolve) =>
      setTimeout(() => {
        resolve();
      }, 600)
    );

    // For placing selected element at its correct position
    while (j >= 0 && parseInt(blocks[j].childNodes[0].innerHTML) > key) {

      // Provide darkblue color to the jth block
      blocks[j].style.backgroundColor = "darkblue";

      // For placing jth element over (j+1)th element
      blocks[j + 1].style.height = blocks[j].style.height;
      blocks[j + 1].childNodes[0].innerText = 
      blocks[j].childNodes[0].innerText;
      j = j - 1;

      // To pause the execution of code for 600 milliseconds
      await new Promise((resolve) =>
        setTimeout(() => {
          resolve();
        }, delay)
      );

      // Provide lightgreen color to the sorted part
      for (var k = i; k >= 0; k--) {
        blocks[k].style.backgroundColor = " rgb(49, 226, 13)";
      }
    }

    // Placing the selected element to its correct position
    blocks[j + 1].style.height = height;
    blocks[j + 1].childNodes[0].innerHTML = key;

    // To pause the execution of code for 600 milliseconds
    await new Promise((resolve) =>
      setTimeout(() => {
        resolve();
      }, delay)
    );

    // Provide light green color to the ith block
    blocks[i].style.backgroundColor = " rgb(49, 226, 13)";
  }
}

// Asynchronous CountingSort function
async function CountingSort(delay = 250) {
  var blocks = document.querySelectorAll(".block");

  var block1 = 0,
    block2 = 0,
    block3 = 0,
    block4 = 0;

  // CountingSort Algorithm
  for (var i = 0; i < blocks.length; i += 1) {
    blocks[i].style.backgroundColor = "#FF4949";
    var value = 
    Number(blocks[i].childNodes[0].innerHTML);

    // Creating element div
    var array_ele = document.createElement("div");

    // Adding style to div
    array_ele.style.height = `${value * 13}px`;

    // Creating label element for displaying
    // size of particular block
    var array_ele_label = document.createElement("label");
    array_ele_label.classList.add("block_id");
    array_ele_label.innerText = value;

    array_ele.appendChild(array_ele_label);

    // Adding block to first bucket
    if (value >= 1 && value <= 5) {
      array_ele.classList.add("firstbucket");
      var container = document.getElementById("one");
      array_ele.style.transform = 
      `translate(${block1 * 30}px)`;
      container.appendChild(array_ele);
      block1++;
    }

    // Adding block to second bucket
    if (value >= 6 && value <= 10) {
      array_ele.classList.add("secondbucket");
      var container = document.getElementById("two");
      array_ele.style.transform = 
      `translate(${block2 * 30}px)`;
      container.appendChild(array_ele);
      block2++;
    }

    // Adding block to third bucket
    if (value >= 11 && value <= 15) {
      array_ele.classList.add("thirdbucket");
      var container = document.getElementById("three");
      array_ele.style.transform = `translate(${block3 * 30}px)`;
      container.appendChild(array_ele);
      block3++;
    }

    // Adding block to fourth bucket
    if (value >= 16 && value <= 20) {
      array_ele.classList.add("fourthbucket");
      var container = document.getElementById("four");
      array_ele.style.transform = 
      `translate(${block4 * 30}px)`;
      container.appendChild(array_ele);
      block4++;
    }

    // To wait for 250 milliseconds
    await new Promise((resolve) =>
      setTimeout(() => {
        resolve();
      }, delay)
    );

    blocks[i].style.backgroundColor = "#6b5b95";
  }

  // Performing insertion sort on every bucket
  await InsertionSort("firstbucket");
  await InsertionSort("secondbucket");
  await InsertionSort("thirdbucket");
  await InsertionSort("fourthbucket");

  // Copying elements from buckets to main array
  for (var i = 0; i < 4; i++) {
    var bucket_idx = 0;
    var block_idx;
    if (i == 0) block_idx =
    document.getElementsByClassName("firstbucket");
    if (i == 1) block_idx = 
    document.getElementsByClassName("secondbucket");
    if (i == 2) block_idx =
    document.getElementsByClassName("thirdbucket");
    if (i == 3) block_idx = 
    document.getElementsByClassName("fourthbucket");
    for (var j = i * 5; j < 5 * (i + 1); j++, bucket_idx++) {
      block_idx[bucket_idx].style.backgroundColor = "red";

      // To wait for 300 milliseconds
      await new Promise((resolve) =>
        setTimeout(() => {
          resolve();
        }, 300)
      );

      blocks[j].style.height = 
      block_idx[bucket_idx].style.height;
      blocks[j].childNodes[0].innerText =
        block_idx[bucket_idx].childNodes[0].innerText;
      blocks[j].style.backgroundColor = "green";

      // To wait for 300 milliseconds
      await new Promise((resolve) =>
        setTimeout(() => {
          resolve();
        }, 300)
      );

      block_idx[bucket_idx]
      .style.backgroundColor = "#6b5b95";
    }
  }
}

// Calling generatearray function
generatearray();

// Calling CountingSort function
CountingSort();

Output: