One Hash Instead of Two

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

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Re: One Hash Instead of Two by McDarren (Abbot) on Feb 06, 2007 at 16:39 UTC
I suspect that this code is probably not really doing what you think it is. You are using $3 as a key to your hash on each iteration. Because hash keys must be unique, each time you find a "src" that you've had before, the previous one will simply be overwritten. I suspect this isn't really what you want. I could suggest an alternative approach, but first I'd like to see some sample data and the output you would expect to get. Cheers, Darren :)	[reply]
Re: One Hash Instead of Two by davorg (Chancellor) on Feb 06, 2007 at 16:30 UTC
Looks like you can just store the count in the same hash. `if ($hash{$3}{src}){ $hash{$3}{count}++; }` [download] Update: McDarren raises a good point. You should probably take a good look at the data structure you create. That's simple enough with Data::Dumper. -- <http://dave.org.uk> "The first rule of Perl club is you do not talk about Perl club." -- Chip Salzenberg	[reply] [d/l]
Re: One Hash Instead of Two by polettix (Vicar) on Feb 06, 2007 at 18:44 UTC
If the count is all you need, you don't need of `%hash` at all: `my %count; while (<FILE>){ next unless /something/; if (/<LONG REGEX>/){ $count{$3}++ if $3; } }` [download] If McDarren is correct, and you want to keep track of all items, you should probably maintain an array inside `$hash{$3}` (and a variable rename would be good in this case), and in this case you would have the count "for free", just looking at how many elements each item has: `my %hashes_for; # More sensible name while (<FILE>){ next unless /something/; if (/<LONG REGEX>/){ push @{$hashes_for{$3}}, { sig => $1, src => $3, proto => $2, dst => $4, port => $5, }; } } # You can now use scalar(@{$hashes_for{whatever}}) instead of $count{w +hatever}` [download] Note: untested code! Flavio perl -ple'$_=reverse' <<<ti.xittelop@oivalf Don't fool yourself.	[reply] [d/l] [select]
Re: One Hash Instead of Two by Dru (Hermit) on Feb 06, 2007 at 21:25 UTC
All, Thank you for your help. This is the code I decided to go with: `my %hash; while (<FILE>){ next unless /Something/; if (/<LONG REGEX>/){ if ($hash{$3}){ $hash{$3}{count}++; next; } $hash{$3} = { sig => $1, src => $3, proto => $2, dst => $4, port => $5, }; } }` [download] davorg, I based my code on yours, just changed it a bit. Thanks for the tip on Data::Dumper, I've heard about it before, just never used it. Very cool McDarren, Believe it or not, one entry from each source is all I really need. I believe this code will speed things up a bit since it will count the source and go to the next one if we already have it. fenLisesi, Thanks, I tend to do that more then I wish to admit. frodo72, Thanks for the code and reply. If I need to build the more complex data structure, I'll probably do something similar to what you gave me. I'll just have to brush up on perlreftut first. -Dru	[reply] [d/l]
Re: One Hash Instead of Two by fenLisesi (Priest) on Feb 06, 2007 at 18:32 UTC
Side issue: you probably want `my (%count, %hash);`. Cheers.	[reply] [d/l]


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