Eliya:

I've modified your solution a bit, as I was uncomfortable with sorting the array for every iteration. For some data sets (very large datasets and/or skewed distributions) the sorting shouldn't be required frequently.

#!/usr/bin/perl
use strict;
use warnings;
use autodie;
use feature ':5.10';

my $top_N = 10;
my $gen_score = sub { 1000 * rand() * rand () };
my $noisy = 0; # 0=quiet, 1=show repl, 2=show add, 3=all traces

# Generate temp data
if (@ARGV or ! -e 'TEMP') {
    my $row_count = shift // 100;
    say "Building temp file with $row_count items" if $noisy;
    open my $FH, '>', 'TEMP';
    printf $FH "ID_%04u %.2f\n", $_, &$gen_score() for 1 .. $row_count
+;
    close $FH;
}

my @top;
my ($cnt_add, $cnt_replace) = (0)x2;

open my $FH, '<', 'TEMP';
while (<$FH>) {
    my ($id, $score) = split ' ';
    if (@top<$top_N) {
        @top = sort { $a->[1] <=> $b->[1] } @top, [ $id, $score];
        say "$.: [$id, $score] ADD => ", scalar(@top),
            " $top[0][0]:$top[0][1] .. $top[-1][0]:$top[-1][1]"
               if $noisy > 1;
        ++$cnt_add;
    }
    elsif ($score > $top[0][1]) {
        @top = sort { $a->[1] <=> $b->[1] } [$id, $score], @top[1 .. $
+#top];
        say "$.: [$id, $score] REPL => ", scalar(@top),
            " $top[0][0]:$top[0][1] .. $top[-1][0]:$top[-1][1]"
               if $noisy;
        ++$cnt_replace;
    }
    else {
        say "$.: [$id, $score] < [ $top[0][0], $top[0][1] ]"
               if $noisy > 2;
    }
}

for (@top) {
    say "$_->[0] : $_->[1]";
}
say "adds: $cnt_add, replacements: $cnt_replace, lines: $.";

[download]

A sample run:

$ perl 919076.pl 1500
ID_0762 : 897.90
ID_1218 : 898.96
ID_1468 : 917.94
ID_0195 : 920.68
ID_0089 : 921.92
ID_0071 : 925.55
ID_0668 : 933.69
ID_1425 : 940.34
ID_0374 : 962.16
ID_0185 : 984.86
adds: 10, replacements: 45, lines: 1500

[download]

Note: Yes, (a) Premature optimization is the root of all evil, (b) I'm not claiming it's faster, as I haven't benchmarked it, and (c) I'm not claiming that yours is "too slow", either. I'm was just scratching an itch. ;^)

...roboticus

When your only tool is a hammer, all problems look like your thumb.

In reply to Re^2: Dealing with Hash Table by roboticus
in thread Dealing with Hash Table by &#350;uRvīv&#337;r

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