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

Good morning Monks, Im fairly new to Perl, I get an output file from a software which is a text file seperate by tabs(although some tabs look longer than others). I can also send an edited version of the file if someone needs the actual file to work with. Here is the code I am using to parse it:

# Opens file 
$file3 = "c:\\users\\plor\\desktop\\Presc_count2.txt";
$file4 = "c:\\users\\plor\\desktop\\Presc_count3.txt";

 open INPUT2, ">", $file4 or die $!;
 open OUTPUT2, "<", $file3 or die $!;

while ($t2 = <OUTPUT2>) {
    @lines = split /s+/, $t2;
    print "$lines[0],$lines[1]\n";
    }
}


close(OUTPUT2);
close(INPUT2);

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When I try to print to test "$lines[0], $lines1" it doesn't give me the output I was expecting, I would've thought it would give me the first two words on that line, instead it prints out either a blank space or nothing(i cant tell if its a space or not). I also tried using split with ('\t') also and I get the same result. Basically I just want each word stored in an element of an array so I can manipulate it. Thanks in advance for any knowledge you guys can pass down to me. -Pao

Replies are listed 'Best First'.
Re: Extracting from output file
by Athanasius (Archbishop) on Aug 15, 2014 at 16:35 UTC

    Hello AllPaoTeam, and welcome to the Monastery!

    You open INPUT2 for writing, i.e. output, and OUTPUT2 for reading, i.e. input. That’s a confusing way to name your variables!

    But the obvious problem is with the first argument to split:

    @lines = split /s+/, $t2;

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    which says split on one or more lowercase ‘s’ characters. I think you meant:

    @lines = split /\s+/, $t2;

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    which splits on whitespace. Beyond that, I doubt that we can help much without seeing the input text.

    BTW, please consider adopting these best practices:

    • use strict; and declare variables with my
    • use warnings;
    • prefer lexical filehandles: open(my $input2, '>', $file4) or die "Cannot open file '$file4' for writing: $!";

    Hope that helps,

    Athanasius <°(((>< contra mundum Iustus alius egestas vitae, eros Piratica,

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[d/l]
[select]
      Thanks for the quick response. I tried "@lines = split /\s+/, $t2;" and I still get the same output. I can send an email of the file to anyone who is willing to help me. Im lost on what to do.
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Re: Extracting from output file
by AppleFritter (Vicar) on Aug 15, 2014 at 18:01 UTC

    Howdy AllPaoTeam, welcome to the Monastery! Athanasius already pointed out that /s+/ in your code should really be /\s+/ if you intend to split on whitespace. (That's all whitespace, BTW, not just tab characters!) And as he furthermore said, a bit of sample data that shows the problem would be good: it doesn't have to be your entire file, just a portion of it that should be handled correctly but isn't.

    You can also use Text::CSV to parse such files by setting the separator to a tab character, like this: 

    #!/usr/bin/perl

use strict;
use warnings;
use feature qw/say/;
use Text::CSV;

my $csv = Text::CSV->new({
    sep_char    => "\t",
    binary      => 1,   # always a good idea
});

while(my $row = $csv->getline(*DATA)) {
    say "$row->[0],$row->[1]";
}

__DATA__
word1   word2   word3
word4   word5   word6

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    This is going to be only useful if your words are separated by precisely one tab character, though, since otherwise you'll get empty fields in between words.

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      I resolved it.... LOL, just being dumb, I was referencing the a non-existing variable, of course its not going to return anything. Yea I dont use strict and warnings because I dont know how to resolve what its complaining about. Thanks again for your help. -Pao
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        Yea I dont use strict and warnings because I dont know how to resolve what its complaining about.

        Ah, that's even more of a reason to use them! If you get errors/warnings that you're not sure what they mean:

        • use diagnostics; to get explanations.
        • Check perldiag (these are the same ones that diagnostics prints, I think).
        • Use the Monastery's Super Search, and/or your favorite web search engine.
        • If you're still not sure, ask a new question on PM!

        You'll learn a lot this way, your Perl will improve, and your scripts will have fewer bugs/unpleasant surprises.

        There's also a book, TheDamian's Perl Best Practices, that may be of interest. It's a bit older by now, but it's got a lot of good advice.

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