sort hash by value

[convenientstore]

What is the best way to sort the hash by value and printing out the top 5 results? For array, I guess you can do something like

@count_s = sort {
     $reportn{$a} <=> $reportn{$b};
} @count_s;

foreach (@count_s[0..4]) {
    print "$_ ====> $reportn{$_}\n";
}

But not sure about hash as below method does not work.
is it just my grammar mistake?

foreach my $hero ( sort keys %total_o) {
   if  ($reportn_o{$hero}) {
         @reportnL = sort { $total_o{$a} <=> $total_o{$b} } values (%t
+otal_o{$hero});
   }
}

for (@reportnL[0..4]) {
  print "$_\n";
}

[salva]

Sorting the full list of items to get just the top n is not the most efficient way, there are better algorithms. See Selection_algorithm.

You can also use Sort::Key::Top instead of implementing those algorithms yourself ;-)

[moritz]

Since you can't reverse a hash in the general case, you can just make a list of lists:

my @list = map { [$_, $hash{$_}] } keys %hash;
# sort it:
@list = sort { $a->[1] cmp $b->[1] };
# now you can print it

[grep]

I'm not quite sure what your doing with all that code, there seem to be quite a few mistakes. Which makes it hard for me to follow.

But as to your main point of the sort not working: You're sending in the values but treating them like keys and trying to do a lookup.
@reportnL = sort { $total_o{$a} <=> $total_o{$b} } values (%total_o{$hero});

Change it to
@reportnL = sort { $total_o{$a} <=> $total_o{$b} } keys %total_o ;

UPDATE: Just noticed his was my 500th post.

[johngg]

for (@reportnL[0..4]) {
  print "$_\n";
}

Your use of an array slice here seems a little unusual, not incorrect but not the way I suspect most would approach the task. I would perhaps do

for ( 0 .. 4 )
{
    print qq{$reportnL[$_]\n};
}

or, more probably

print qq{$reportnL[$_]\n} for 0 .. 4;

I hope this is of interest.

Cheers,

JohnGG