in reply to Sorting Index of An Array

Use a Schwartzian transform - like this: (update: but see salva's comment below for a better approach) 

@sorted = map {$_->[0]}
          map {
             $i=0; sort {$b->[1]<=>$a->[1]} map {[$i++,$_]} splice (@s
+im,0,9)
          } 0..8;

print "\@index_ordered =(\n";
for(0..8) {
    print " " x 4, join(', ', splice (@sorted,0,9) ),"\n";
}
print ");\n";

[download]

Output: 

@index_ordered =(
    0, 1, 3, 2, 4, 5, 7, 8, 6
    1, 0, 3, 8, 2, 4, 7, 6, 5
    2, 3, 8, 0, 1, 4, 7, 5, 6
    3, 0, 1, 2, 8, 7, 6, 4, 5
    4, 8, 7, 0, 1, 2, 6, 3, 5
    5, 0, 7, 1, 2, 3, 6, 8, 4
    6, 7, 8, 3, 4, 1, 2, 0, 5
    7, 6, 8, 3, 4, 0, 1, 5, 2
    8, 7, 6, 3, 4, 1, 2, 0, 5
);

[download]

For equal elements in each row of @sim the order of their indices is undetermined. Note that this is destructive to @sim - it will be empty after the sort.

While the above code DWYM, you would have been better off having an array of arrays in the first place.

--shmem 

_($_=" "x(1<<5)."?\n".q·/)Oo.  G°\        /
                              /\_¯/(q    /
----------------------------  \__(m.====·.(_("always off the crowd"))."·
");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}

Replies are listed 'Best First'.
Re^2: Sorting Index of An Array
by salva (Canon) on May 14, 2007 at 12:08 UTC
    Use a Schwartzian transform

    To sort lists of nine elements, applying the ST is probably counterproductive. And anyway, for that particular problem, using a Orcish Maneuver would be more suitable: 

    my @index_sorted = map {
  my @row = splice @sim, 0, N;
  sort { $row[$b] <=> $row[$a] } 0..(N-1);
} 0..(M-1);

    [download]
[reply]
[d/l]
      Just a nit - while your approach is far better than mine and less convoluted, there's no OR and no cache, so there's no Orcish (or-cache) Maneuver. That would be (from Shlomo Yona's Perl lectures 2002):

      The Orcish Maneuver -- example

      keys my %or_cache = @in;
@out = sort {
    ($or_cache{$a} ||= KEY($a))
    cmp
    ($or_cache{$b} ||= KEY($b))
} @in;

      [download]

      The first part of the sortsub sees if the sortkey for $a is cached.

      If not, it extracts the value of the sortkey from the operand and caches it.

      The sortkey for $a is then compared to the sortkey for $b.

      Anyways, salva++ for simplifying things :-)

      --shmem 

      _($_=" "x(1<<5)."?\n".q·/)Oo.  G°\        /
                              /\_¯/(q    /
----------------------------  \__(m.====·.(_("always off the crowd"))."·
");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}
[reply]
[d/l]

In Section Seekers of Perl Wisdom