unitproc/bkt-get_median

   1 #!/usr/bin/env bash
   2
   3 read_stdin() {
   4     # Desc: Consumes stdin; outputs as stdout lines
   5     # Input: stdin (consumes)
   6     # Output: stdout (newline delimited)
   7     # Example: printf "foo\nbar\n" | read_stdin
   8     # Depends: GNU bash (version 5.1.16)
   9     # Version: 0.0.1
  10     local input_stdin output;
  11
  12     # Store stdin
  13     if [[ -p /dev/stdin ]]; then
  14         input_stdin="$(cat -)";
  15     fi;
  16
  17     # Store as output array elements
  18     ## Read in stdin
  19     if [[ -n $input_stdin ]]; then
  20         while read -r line; do
  21             output+=("$line");
  22         done < <(printf "%s\n" "$input_stdin");
  23     fi;
  24
  25     # Print to stdout
  26     printf "%s\n" "${output[@]}";
  27 }; # read stdin to stdout lines
  28 get_median() {
  29     # Desc: Gets the median from integers or floats read from stdin
  30     # Input:  stdin   newline-delimited integers or floats
  31     # Output: stdout  float
  32     # Depends: GNU Coreutils 8.32 (sort), bc 1.07.1
  33     # Depends: BK-2020-03: read_stdin() 0.0.1,
  34     # Version: 0.0.1
  35
  36     # Read stdin
  37     list="$(read_stdin)";
  38
  39     # Sort list
  40     list="$(printf "%s\n" "$list" | sort -n)";
  41
  42     # Get list length
  43     list_lc="$(printf "%s\n" "$list" | wc -l)";
  44
  45     # Get number of lines to trim from start and end
  46     if [[ $((list_lc % 2)) -eq 0 ]]; then
  47         # If even
  48         trim=$(( list_lc / 2 - 1 ));
  49         flag_even="true";
  50     else
  51         # If odd
  52         trim=$(( list_lc / 2 ));
  53     fi;
  54
  55     # Trim lines
  56     list="$(printf "%s\n" "$list" | tail -n+$((trim+1)) | head -n-$((trim)) )";
  57
  58     # Get median
  59     if [[ "$flag_even" == "true" ]]; then
  60         ## Average remaining two lines
  61         l1="$(printf "%s\n" "$list" | head -n1)";
  62         l2="$(printf "%s\n" "$list" | tail -n1)";
  63         median="$( echo "( $l1 + $l2 ) / 2" | bc -l; )";
  64     else
  65         ## Median is simply remmaining line
  66         median="$list";
  67     fi;
  68
  69     # Output median
  70     printf "%s" "$median";
  71
  72     # Author: Steven Baltakatei Sandoval
  73     # License: GPLv3+
  74 }; # Returns median float from a list
  75
  76 # Test
  77 shuf -i1-100 -n49 | get_median; printf "\n";
  78 printf "17\n5\n11.1111\n3.141592\n2\n343.4343434343434343\n" | get_median; printf "\n";