median

Calculates the median (middle value) of an array of numbers. Finds the middle value when numbers are arranged in ascending order. For arrays with even length, returns the average of the two middle values. Handles empty arrays by returning NaN following statistical convention.

Signature

const median: (numbers: readonly number[]) => number

Parameters

Name	Type	Description
numbers	-	Array of numbers to find median from (readonly)

Returns

Median value, or NaN if array is empty

Examples

Basic median calculations

import { median } from '@winglet/common-utils';

// Odd length arrays (middle element)
console.log(median([1, 3, 5])); // 3
console.log(median([7, 1, 9, 3, 5])); // 5 (sorted: [1,3,5,7,9])

// Even length arrays (average of middle two)
console.log(median([1, 2, 3, 4])); // 2.5 ((2+3)/2)
console.log(median([10, 20])); // 15 ((10+20)/2)

Edge cases and real-world data

// Empty array
console.log(median([])); // NaN

// Single element
console.log(median([42])); // 42

// Unsorted input (gets sorted automatically)
console.log(median([5, 1, 9, 3])); // 4 (sorted: [1,3,5,9], median: (3+5)/2)

// Real data: test scores
console.log(median([85, 90, 78, 92, 88])); // 88
console.log(median([1.1, 2.2, 3.3, 4.4])); // 2.75

Playground

import { median } from '@winglet/common-utils';

// Odd length arrays (middle element)
console.log(median([1, 3, 5])); // 3
console.log(median([7, 1, 9, 3, 5])); // 5 (sorted: [1,3,5,7,9])

// Even length arrays (average of middle two)
console.log(median([1, 2, 3, 4])); // 2.5 ((2+3)/2)
console.log(median([10, 20])); // 15 ((10+20)/2)

Notes

Statistical Properties:

• Less sensitive to outliers compared to mean
• Represents the 50th percentile of the dataset
• For odd-length arrays: returns the exact middle element
• For even-length arrays: returns average of two middle elements
• Returns NaN for empty datasets

Use Cases:

• Statistical analysis and data science
• Robust central tendency measurement
• Salary and income analysis (less skewed by extremes)
• Performance benchmarking and metrics
• Quality control and process monitoring
• Financial analysis (median house prices, returns)

Performance: O(n log n) time complexity due to sorting, O(n) space complexity for the sorted copy. Consider using a selection algorithm for better performance if median calculation is frequent.