Hash sorting by values

cajun has asked for the wisdom of the Perl Monks concerning the following question:

This code is slightly modified version of miyagawa's code found at CodeRed notifier. Because I wasn't able to understand his regex to get $ip & $datetime, I chose another method to accomplish the task.

What I have thus far, produces output something like this:

2001-08-03 17:57:28     66.120.120.203
2001-08-02 14:15:20     66.121.185.222
2001-08-05 16:51:28     66.24.60.57
2001-08-04 02:35:47     66.30.84.177
2001-08-01 18:52:22     66.74.16.2
2001-08-02 15:38:24     66.92.175.55
[download]

What I would like to do is have the output sorted by $datetime (the values of the hash %ip2date, rather than the keys). Thus far, I've not been able to see how to do this.

Here's what I have thus far:

#!/usr/local/bin/perl -w 

use strict;
use Config;
use Getopt::Std;
use Mail::Sendmail;


getopts('f:', \my %opt);


my $from = 'me@myaddress.com';
my $to   = 'me@myaddress.com';

my %ip2date;  # $ip=key   $datetime=value
while (<>) {
    next unless m!GET /default\.ida ?[XN]+!;
    my @datetime=(split)[0,1];
    my $datetime=join(' ',@datetime);
    my $ip=(split)[2];
    next if $ip2date{$ip};
    $ip2date{$ip} = $datetime;
}

my $message = join '', map { "$ip2date{$_}\t$_\n" } sort keys %ip2date
+;
print "$message\n";

sendmail(
    To      => $to,
    From    => $from,
    Message => $message,
    Subject => "CodeRed Infection Notification",
);
[download]

Comment on Hash sorting by values Select or Download Code

Replies are listed 'Best First'.
Re: Hash sorting by values by tachyon (Chancellor) on Aug 08, 2001 at 15:02 UTC
The Perl FAQ can be really useful for answers to questions like this. If you have a look you will see: perlfaq4: Data Manipulation A quick look at the section on hashes gives you: How do I sort a hash (optionally by value instead of key)? The FAQs are great. Check 'em out when you have a moment. cheers tachyon s&&rsenoyhcatreve&&&s&n.+t&"$'$`$\"$\&"&ee&&y&srve&&d&&print	[reply]
Re: Hash sorting by values by blakem (Monsignor) on Aug 08, 2001 at 13:25 UTC
In general you can sort a hash by value using a construct such as: `for my $key (sort {$hash{$a} cmp $hash{$b}} (keys %hash)) { print "Key = $key, Value = $hash{$key}\n"; }` [download] though I don't see why you want to do it in the code above. update ok, I get it now... $message isn't in its final form above... I was wondering why you wanted the body of your email to consist of value sorted elements in the %ip2date hash. -Blake	[reply] [d/l]


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