Get median of unsorted array in one line of BASH

Question

I haven't been able to find any simple implementations for finding the median of an array. How can do do this is bash without reinventing the wheel?

If currently using this:

median() {
  arr=$1
  nel=${#arr[@]}
  if (( $nel % 2 == 1 )); then     # Odd number of elements
    val="${arr[ $(($nel/2)) ]}"
  else                            # Even number of elements
    val="$(( ( arr[$((nel/2))] + arr[$((nel/2-1))] ) / 2 ))"
  fi
  printf "%d\n" "$val"
}

For some reason I still can't figure out, it's returning incorrect values, and it seems overly complicated for something so simple. I feel like there has to be a way to do this in one line.

Answer 1

I think you want something like this:

#!/bin/bash
median() {
  arr=($(printf '%d\n' "${@}" | sort -n))
  nel=${#arr[@]}
  if (( $nel % 2 == 1 )); then     # Odd number of elements
    val="${arr[ $(($nel/2)) ]}"
  else                            # Even number of elements
    (( j=nel/2 ))
    (( k=j-1 ))
    (( val=(${arr[j]} + ${arr[k]})/2 ))
  fi
  echo $val
}

median 1
median 2 50 1
median 1000 1 40 50

Sample Output

1
2
45