The first problem is the easier one. You can get what you're looking for using nested hashes (e.g. "hashes of hashes"). At each level, the values in the hash are references (similar to pointers) to the hashes at the next layer "in". At the deepest layer, the values are simply values that have some arbitrary meaning.

So in the case of %weather_archive, to store the data you show, I would do:

$weather_archive{'2003'}{'April'}{'15'}{'High'} = '73f';
$weather_archive{'2003'}{'April'}{'15'}{'Low'} = '49f';
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NOTE: That's not to say that resources haven't been expended. Perl will allocate a certain amount of memory to all of these layered hashes - and four layers is pretty deep - but it shouldn't be too hideous. I'm using four-deep hashes in one of my Perl scripts without any trouble.

Anyway, to print out the data, you could do something like this (although hopefully not the same, since I think you could do the print part better than this):

foreach $year ( sort keys %weather_archive ) {
  print "$year\n";
  foreach $month ( keys %{$weather_archive{$year}} ) {
    print "  $month\n";
    foreach $day ( sort keys %{$weather_archive{$year}{$month}} ) {
      print "$day\n";
      foreach $measurement ( keys %{$weather_archive{$year}{$month}{$d
+ay}} ) {
        print "$measurement:  $weather_archive{$year}{$month}{$day}{$m
+easurement}\n";
      }
    }
  }
}
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As for reading in the data, that's just a matter of making sure that wherever you get your info, $year, $month, $day, $var, and $value are correct before you do:

$weather_archive{$year}{$month}{$day}{$var} = $value;
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Make sense?

--Rhys

Rhys, that makes perfect sense. I was making my life difficult by not storing the data in the format I wanted to read it in. Duh!

I'll be studying perlref and perlreftut hard until I feel like I'm ready for the exam at the end of the semester. ;-)

Thanks davido and snax!

:) I only made the comment because it seemed that you were thoughtful enough to actually care to learn the whys and not just the hows. Glad to see my humor/advice wasn't wasted. Honestly, digging into the perldocs, though intimidating at first (certanly was for me), will really open your eyes to the Perl way. The perldocs are an important part of separating the script kiddies from the determined seekers of wisdom.

One of the best things I ever did toward learning what little I already know was to load the docs into my PDA in HTML format so that I could use it as a digital reference book. Somehow that works better for me than sitting at the notebook reading them. I refer to them often; at least as often as the Camel book.

References are also intimidating at first. I had enough background in C (with pointers) to catch the general concepts quickly, but I'm still all thumbs with things like creating objects. But hopefully a little more fiddling and reading, and I'll gain some better perspective in that area as well.

Keep up the learning process. Though I can't speak for the Monastery, I can speak for myself in saying I always welcome questions that are accompanied by an actual desire to understand the subject, and that make me think. To that end, keep them coming. :)



Dave

"If I had my life to do over again, I'd be a plumber." -- Albert Einstein

foreach $date ( @weather_days ) {
    $weather_archive{$date->{Year}}{$date->{Month}}{$date->{Day}} = 
        ( $date->{High},
          $date->{Low},
          $date->{Season},
          $date->{Wind},
          $date->{Bar} );
}
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I'm sure that my snippet can be done with a map too but this is good enough. Oh, and that's the part that perlreftut would give you a better grasp on. Go ahead and read perlreftut and perlref as mentioned earlier so that you won't flunk the exam at the end of the semester. Producing working code today, and understanding the concepts behind it are two different things. This is something that you will use a lot once you understand the concepts. Failing to dig until the concept sinks in is going to cripple your progress.