Calculating median - javascript

Question

I\'ve been trying to calculate median but still I\'ve got some mathematical issues I guess as I couldn\'t get the correct median value and couldn\'t figure out

Answer 1

Short and sweet.

Array.prototype.median = function () {
  return this.slice().sort((a, b) => a - b)[Math.floor(this.length / 2)]; 
};

Usage

[4, 5, 7, 1, 33].median()

Works with strings as well

["a","a","b","b","c","d","e"].median()

Answer 2

Simple solution:

function calcMedian(array) {
  const {
    length
  } = array;

  if (length < 1)
    return 0;

  //sort array asc
  array.sort((a, b) => a - b);

  if (length % 2) {
    //length of array is odd
    return array[(length + 1) / 2 - 1];
  } else {
    //length of array is even
    return 0.5 * [(array[length / 2 - 1] + array[length / 2])];
  }
}

console.log(2, calcMedian([1, 2, 2, 5, 6]));
console.log(3.5, calcMedian([1, 2, 2, 5, 6, 7]));
console.log(9, calcMedian([13, 9, 8, 15, 7]));
console.log(3.5, calcMedian([1, 4, 6, 3]));
console.log(5, calcMedian([5, 1, 11, 2, 8]));

Answer 3

Here's another solution:

function median(numbers) {
    const sorted = numbers.slice().sort((a, b) => a - b);
    const middle = Math.floor(sorted.length / 2);

    if (sorted.length % 2 === 0) {
        return (sorted[middle - 1] + sorted[middle]) / 2;
    }

    return sorted[middle];
}

console.log(median([4, 5, 7, 1, 33]));