A bit over-engineered in this case. Take the same assumption as yours, the code could be much simpler:

my @new = sort {(split /\s+/, $b)[0] <=> (split /\s+/, $a)[0]} @old;

[download]

And it is faster:

use Data::Dumper;
use strict;
use warnings;

my @old = ("10.5 AA", "10.6 AA", "9 AC", "2 BB");  
my $t0 = time();
for (1..200000) {#yours
    my @new = map { $_->[0] }
          sort { $b->[1] <=> $a->[1] }
          map { [ $_, (split( /\s+/, $_, 2 ))[0] ] }
          @old;
}
print time() - $t0, "\n";

$t0 = time();
for (1..200000) {#mine
    my @new = sort {(split /\s+/, $b)[0] <=> (split /\s+/, $a)[0]} @ol
+d; 
}
print time() - $t0, "\n";

[download]

I ran four times, yours took: 13, 14, 14, 13 seconds, when mine took 8, 10, 11, 9 seconds.

In reply to Re^2: Numeric Sort for Stringified Value (How to Avoid Warning) (Use the ST) by pg
in thread Numeric Sort for Stringified Value (How to Avoid Warning) by neversaint

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