Count Numbers Less Than or Equal to Given Value Using Percentile in JavaScript

In this article, you will understand how many numbers in the given array are less/equal to the given value using the percentile formula. We calculate the percentage of numbers in the given array less or equal to the number using the formula ?

Percentile = (n/N) * 100 

Where, n is the number of values below x and N is the total number of values.

Example 1

In this example, we use a for-loop to iterate the array and check each element whether the value is less, equal or greater than the given input value.

const calculationPercentile = (inputArray, val) => {
   let resultValue = 0;   
   for (let i in inputArray) {
      resultValue = resultValue + (inputArray[i] < val ? 1 : 0) +
      (inputArray[i] === val ? 0.5 : 0);
   }   
   let displayResult = (resultValue / inputArray.length) * 100;
   console.log("
The percentile value is ")
   console.log(displayResult);
};   
const inputArray = [3,4,5,6,7,8]
console.log("The array is defined as :", inputArray)
   
// calling the function calculationPercentile
calculationPercentile(inputArray, 6);

Explanation

• Step 1 ?Define an array of numbers and define an input value.

• Step 2 ?Define a function ?calculationPercentile' that takes an array and a value as input.

• Step 3 ?In the function, define a variable ?resultValue' that holds the count of numbers of the array less than the inputValue.

• Step 4 ?Finally apply the percentile formula: (resultValue / inputArray.length) * 100 and display the result.

Example 2

In this example, we use reduce() method which will traverse the array of numbers and convert it into a single entity

const calculationPercentile = (inputArray, inputValue) =>
(100 *
inputArray.reduce(
   (tempValue, v) => tempValue + (v < inputValue ? 1 : 0) +
   (v === inputValue ? 0.5 : 0),
   0
)) /
inputArray.length;
const inputArray = [3,4,5,6,7,8]
console.log("The array is defined as :", inputArray)
   
let inputValue = 6
console.log("The array is defined as :", inputValue)
   
console.log("
The percentile value is ")
console.log(calculationPercentile(inputArray, inputValue))

Explanation

• Step 1 ?Define an array of numbers and define an input value.

• Step 2 ?Define a function ?calculationPercentile' that takes an array and a value as input.

• Step 3 ?In the function, use the reduce() method to get the values of the array lesser than the input value, divide the number by the array length and multiply it by 100.

• Step 4 ?Call the function and display the result.