Re^2: Speeding up perl script

This is basically the code I'm talking about. Looping through a number of files, reading them (this routine is quick), and looping through all parameter names in each file, checking if they already exists in the global @names array and take action depending on the result. It is this check (find_element) that I want to speed up. Any ideas? If hash is a good alternative, could you please explain the difference compared to an array? New at perl so I'm not so familiar with all expressions... Thank you!

    foreach $filename (@input_names) #Go through input files
    {
        
        ($names_ref,$data_ref) = &read_file($filename);
        @tmp_names = @$names_ref;
        @tmp_data = @$data_ref;

        foreach $name (@tmp_names) #Go through lines of current input 
+file
        {
            $index = &find_element($name, @names); #Check if variable 
+is already present in name array (time consuming!)
            if ($index==-1) #Name not present, put both name and data 
+in array
            {
                push(@names,$name);
                push(@data,$tmp_data[$tmp_index]);
            }
            else #Name present, only replace data for the name
            {
                $data[$index] = $tmp_data[$tmp_index];    
            }
            $tmp_index++;
        }

    }
[download]

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Re^3: Speeding up perl script by Corion (Patriarch) on Jan 28, 2009 at 09:13 UTC
The main difference between a hash and an array is that an array is indexed by number while a hash is indexed by name. So where a lookup in an array is fast if you know the position of the value, a lookup in a hash is fast if you know the "name" of the value, that is, the (string) key the value is associated with.	[reply]
Re^3: Speeding up perl script by jettero (Monsignor) on Jan 28, 2009 at 10:10 UTC
Yeah, you probably want something more like this, or something similar to it. `my %hash; while(my $line = <>) { my ($name, $value) = split m/something goes here/, $line; die "error: value already defined!" if exists $hash{$name}; $hash{$name} = $value; }` [download] -Paul	[reply] [d/l]