Code from the column "Sorting with the Schwartzian Transform" published in "Unix Review" issue 64 (May 2006)

schwartzian_transform.pl

#!/usr/bin/env perl

# Based on code from http://www.stonehenge.com/merlyn/UnixReview/col64.html

use strict;
use warnings;

use Data::Dumper;

print "Input \$str\n";
my $str =
  "eir      11   9   2    6    3    1     1  81%  63%    13\n" .
  "oos      10   6   4    3    3    0     4  60%  70%    25\n" .
  "hrh      10   6   4    5    1    2     2  60%  70%    15\n" .
  "spp      10   6   4    3    3    1     3  60%  60%    14\n";
print Dumper($str);

print "\nSplit \$str into a list of lines\n";
my @lines = split /\n/, $str;
print Dumper(\@lines);

print "\nMap lines plus extracted sort key into a list of arrayrefs\n";
my @annotated_lines = map { [$_, (split)[-1]] } @lines;
print Dumper(\@annotated_lines);

print "\nSort lines using the sort key\n";
my @sorted_lines = sort { $a->[1] <=> $b->[1] } @annotated_lines;
print Dumper(\@sorted_lines);

print "\nExtract lines, i.e. remove sort key\n";
my @clean_lines = map { $_->[0] } @sorted_lines;
print Dumper(\@clean_lines);

print "\nCreate \$result string:\n";
my $result = join "\n", @clean_lines;
print Dumper($result);

print "\n\nAll the above in one go using the Schwartzian Transform\n";
my $result_using_schwartzian_transform =
  join "\n",
  map { $_->[0] }
  sort { $a->[1] <=> $b->[1] }
  map { [$_, (split)[-1]] }
  split /\n/,
  $str;
print Dumper($result_using_schwartzian_transform);