#! /usr/bin/env perl
#
# 偏差値算出サンプル
#
use strict;
main();

sub main
{
    my %hash = (
        'a' => 97,
        'b' => 40,
        'c' => 65,
        'd' => 22,
        'e' => 21,
        'f' => 33,
        'g' => 78,
        'h' => 0,
        'i' => 100,
    );

    # 平均
    my $cnt = 0;
    my $sum = 0;
    for my $key(keys %hash) {
        $cnt++;
        $sum += $hash{$key};
    }
    my $ave = $sum / $cnt;
    print "平均 : $ave点\n";

    # 標準偏差
    my $asum = 0;
    for my $key(keys %hash) {
        $asum += ($hash{$key} - $ave) ** 2;
    }
    my $sdev = sqrt($asum / $cnt);
    print "標準偏差 : $sdev\n";

    # 偏差値
    for my $key(sort keys %hash) {
        my $dev = ($hash{$key} - $ave) * 10 / $sdev + 50;
        print $key . " : " . $hash{$key} . '点 (偏差値' . int($dev) . ")\n";
    }
}