counting unique elements of an array

mmittiga17 has asked for the wisdom of the Perl Monks concerning the following question:

Hi All, I am struggling to create a report that will parse a bunch of files 1 at time and report back the number transactions per unique bank code. Bank code is the first field in the separated my \t in each file. Here is the code I have which is not counting correctly. =====

open (logfile, ">>$LogName");
        while ($line = <cfile>) {
        $counter++;
        $BankCode=(split(/\t/,$line))[0];
         print "$BankCode\n";
         push(@bc ,"$BankCode");
}        
my %count;
map { $count{$_}++ } @bc;
$count = return %count;

map {print logfile  map {print logfile  "$ClientCode[$clientindex][0]\
+t$_\t$FileType[$fileindex][1]\t$CurrFile\t${count{$_}}\t$CurrZipFile\
+t$yyyymm\t$onDemand\n"} sort keys(%count);
=====
$_  = the BankCode in the print line
[download]

Any suggestions? It appears to add the count from the last unique bankcode from the last file to the new files bankcode count. Thanks in advance

Comment on counting unique elements of an array Download Code

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Re: counting unique elements of an array by toolic (Bishop) on Jan 30, 2008 at 17:32 UTC
Not sure why yours isn't working, but is this what you're looking for? `#!/usr/bin/env perl use warnings; use strict; my @bc; my %count; while (<DATA>) { my $BankCode = (split /\t/)[0]; $count{$BankCode}++; } for (keys %count) { print "$_ $count{$_}\n" } __DATA__ code1 fooz barz code2 fooz barz code1 fooz barz code3 fooz barz code1 fooz barz code1 fooz barz` [download] prints: `code3 1 code2 1 code1 4` [download]	[reply] [d/l] [select]
Re: counting unique elements of an array by moritz (Cardinal) on Jan 30, 2008 at 17:30 UTC
`$count = return %count;` Maybe you meant: `my $count = scalar keys %count;` It appears to add the count from the last unique bankcode from the last file to the new files bankcode count That sounds like a scoping issue. Are you using strict and warnings? You should be. And it's impossible to tell what went wrong without seeing the whole of the loop. Including the places where the variables are defined for the first time. BTW your map in void context looks a bit scary - your intention might be clearer if you used a `for` loop. If you like short code, you can also write `@count{@bc} = undef;` instead ;-)	[reply] [d/l] [select]
Re: counting unique elements of an array by apl (Monsignor) on Jan 30, 2008 at 17:59 UTC
toolic gave you a great solution. I just wanted to mention a few minor things: Internal variable $. could be used instead of $counter. Internal variable $_ could be used in lieu of $line. The print isn't needed after you determine the split worked properly.	[reply]