On Wed, Oct 24, 2001 at 04:15:08PM +0100, Lucy McWilliam wrote:
>
> Hmm, this is where admit I'm crap and provide the CFT club with something
> to ponder. I have made pairwise comparisons of a few thousand flies
> and stored the similarity scores in a *large* file in a particular order
> (to save me storing their names and making the file even bigger).
>
> e.g.
> fly0_versus_fly0_score
> fly0_versus_fly1_score
> fly0_versus_fly2_score
> fly1_versus_fly1_score
> fly1_versus_fly2_score
> fly2_versus_fly2_score
>
> What I'd like to end up with for each comparison is 2 numbers - the
> position of fly_X in a list of numerically descending fly_Y scores -
> e.g. highest score gets rank 1 - and vice versa. Self comparisons
> should not be included.
At the moment your datafile contains x ** 2 + x / 2 data items. If you're
happy with an array with that many scalars in it then you can probably get
a speed up from something like this:
Firstly read all the data into an array, then get rid of the prepare sub.
$N = 3000; # number of flies
my @rank;
my @line = <FILE>;
chomp @line;
for my $i (0 .. ($N - 1)) {
my %scores;
my $index = $i;
for my $j (0 .. ($N - 1)) {
$scores{$index} = $line[$index];
$index += $j < $i ? $N - $j - 1 : 1;
};
my $rank;
foreach $key (sort { $scores{$b} <=> $scores{$a} } keys (%scores)) {
$rank[$key] .= " $rank" if ($rank++);
}
}
foreach my $n (0 .. $#line) {
print $line[$n] . $rank[$n];
}
cheers
Andrew
