I can see you've had problems with the code. It would have been useful to provide an algorithm for calculating what you refer to as Average Precision. I've made a guess at what you've attempting to achieve in the following script. If it's not right, please provide more concrete information.

#!/usr/bin/env perl

use strict;
use warnings;

my %result = ();
my $wanted_relaz = q{hyper};

my $last_u = q{};
my $u_count = 0;
my $relaz_count = 0;
my $precision = 0;

my ($rank, $u, $relaz);

while (<DATA>) {
    ($rank, $u, $relaz, undef) = split;

    if ($u ne $last_u) {
        if ($last_u) {
            $result{$last_u} = $precision / $relaz_count;
        }

        $last_u = $u;
        $u_count = 0;
        $relaz_count = 0;
        $precision = 0;
    }

    ++$u_count;

    if ($relaz eq $wanted_relaz) {
        ++$relaz_count;
        $precision += $u_count / $rank;
    }
} 

$result{$u} = $precision / $relaz_count;

for my $key (sort keys %result) {
    print qq{$key\t$wanted_relaz\t$result{$key}\n};
}

__DATA__
1    acacia-n    hyper    tree-n    0.838364743354488
2    acacia-n    hyper    plant-n    0.740581661563839
3    acacia-n    mero    wood-n    0.687569086370938
4    acacia-n    mero    flower-n    0.650909477491374
5    acacia-n    coord    oak-n    0.610092594991099
6    acacia-n    coord    pine-n    0.537690234715029
7    acacia-n    mero    branch-n    0.510899195919917
8    acacia-n    mero    root-n    0.491198721010063
9    acacia-n    coord    willow-n    0.481680704877001
1    ant-n    hyper    animal-n    0.634580215370739
2    ant-n    hyper    insect-n    0.53621081509255
3    ant-n    mero    head-n    0.535980012877533
4    ant-n    mero    body-n    0.505827598873949
5    ant-n    coord    bee-n    0.481918895790599
1    apricot-n    hyper    fruit-n    0.76748797529242
2    apricot-n    coord    apple-n    0.685155565667883
3    apricot-n    mero    juice-n    0.560337418489082
4    apricot-n    coord    banana-n    0.559525300446683
[download]

Here's the output:

$ pm_avg_precision.pl
acacia-n    hyper    1
ant-n    hyper    1
apricot-n    hyper    1
[download]