Split and hash

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

Greetings, I am a newbie, so please bear with me if this is too simple to be posted. When I run the following code, I don't get any output. I have included the expected output at the bottom. What am I missing? I could directly "print $version", but I need to access through a hash(key) for additional processing. Using Perl version 5.8.8

use strict ;
my %seen = ();

    while(<DATA>){
        chomp;

                my($file,$version) = split(/vobx/,$_);
                 print "$seen{$file} \n";
                 
}

__DATA__
/view/d602_edf3/vobx/copy/pp/copy/ticrwpth
/view/d602_edf3/vobx/copy/pp/copy/ticrwptr
/view/d602_edf3/vobx/copy/pp/copy/tirrwphz
/view/d602_edf3/vobx/copy/pp/copy/tirrwprq
[download]

Expected output : /copy/pp/copy/ticrwpth /copy/pp/copy/ticrwptr /copy/pp/copy/tirrwphz /copy/pp/copy/tirrwprq

I understand I can get the string I need from the $version. But like I mentioned, I need to be able to access it as a $hash{$key}. I am not sure why this code is not working.

Here is what I am actually trying to do. Assume that, I have a file which looks as follows file1@@/main/trunk/1 file2@@/main/trunk/2 file2@@/main/trunk/3 file1@@/main/trunk/2 file1@@/main/trunk_2/1 If the file name (before @@) is unique, I need to capture that straight away. If there is trunk_2, that line trumps other lines which have the same file name. If there is no trunk_2, I need to get the line with just "trunk" which has the highest numeric at the end after the last "/". There might be more than one line for trunk_2 with different numeric at the end, in which case, I need to get the higher numeric among all lines with same file names before "@@". So, the output should be file1@@/main/trunk_2/1 file2@@/main/trunk/3 Hope this helps.

Comment on Split and hash Download Code

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Re: Split and hash by almut (Canon) on Dec 22, 2009 at 21:41 UTC
You haven't assigned anything to `%seen`. Maybe add `$seen{$file} = $version;` [download] before the `print` statement. Or even `push @{ $seen{$file} }, $version; print "@{$seen{$file}} \n";` [download] as the `$file` part (hash key) seems to be the same in all cases (at least for the sample data). The latter would create an array for a hash entry/key `"/view/d602_edf3/"` with the array holding all values of `$version`... Maybe you could elaborate on what exactly you're trying to achieve.	[reply] [d/l] [select]
Re: Split and hash by ikegami (Patriarch) on Dec 22, 2009 at 21:36 UTC
You get four warnings and four blank lines for output because `%seen` doesn't contains anything. The text you want to is in `$version`. If you want it in `%seen`, put it in `%seen`.	[reply] [d/l] [select]