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How do I extract the number of times a value appears in a hash?

( #30630=categorized question: print w/ replies, xml ) Need Help??
Contributed by v on Sep 01, 2000 at 00:39 UTC
Q&A  > hashes


Description:

I'm creating a hash that contains IP_Address:Size objects. The same IP_Address occurs many times, as is Size. i want to know the following:
  • how many times each IP_Address appears
  • sum of Size for any given IP_Address

Answer: How do I extract the number of times a value appears in a hash?
contributed by BlaisePascal

Is the "IP_Address:size" blocks the hash values, or the hash keys?

Assuming the the IP_Address:size blocks are the hash values (say, you were keying off of a connection ID, or something), then you could do something like:

my %counts; my %sizes; for (values %inhash) { my ($ip, $size) = split /:/; next unless defined $ip; $counts{$ip}++; $sizes($ip)+= $size; } for $ip (keys $counts) { my ($count, $size) = ($counts{$ip},$sizes{$ip}; print "IP Address $ip appeared $count times, for a total size of $si +ze\n"; }
Does that help?
Answer: How do I extract the number of times a value appears in a hash?
contributed by ton

Assuming that "IPaddr:Size" are the values:

map {if /^(.*):(\d*)$/ {$count{$1}++;$size{$1}+=$2;}} values(%hash);
This will place results in the %count and %size hashes, keyed by IP address. If "IPaddr:Size" are the keys, just replace the 'values' with 'keys' in the fragment above.
Answer: How do I extract the number of times a value appears in a hash?
contributed by dsb

Pardon the building of the hash

#! /usr/bin/perl %hash = ( '1' => 'foo', '2' => 'bar', '3' => 'foo', '4' => 'foo', ); %count; foreach $key ( keys %hash ) { $val = $hash{$key}; $count{$val}++; } foreach $key1 ( keys %count ) { print $key1 . " appears " . $count{$key1} . " times\n"; }

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