Extract word

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

####################################################################
##                               MAIN
####################################################################

my $input_file = get_file ('no_sense_hogwash.txt'); #define an input f
+ile

my %ignore = (

    'and' => 1,

  );

while($input_file =~ /(\w[\w'-]*)/g) {
  
  my $word = lc $1;
  
  if (defined $ignore{$word}) {
    
    next;
    
  }
  
}

print "$input_file\n";

####################################################################
##                               SUBS
####################################################################

sub get_file { #to open a file (currently restriction.txt)
               #and store all the data within $sequence

  my ($input_file) = @_;
  
  open (IN, $input_file) or die "Cannot open $input_file for reading: 
+$OS_ERROR\n"; #open a filehandle or die  
  
  my $sequence = ''; 
  
  foreach my $line (<IN>) { #for each line in the filehandle IN

    if ($line =~ /^\s*$/) { # discard blank line
  
      next; #skip the rest of the statement block and continue with th
+e next iteration of the loop
    
    }

    $sequence .= $line # add (concatenate) to a string sequence 
      
  }
  
  return $sequence; #return the string sequence
  
  close IN;

}
[download]

I'd like to extract from a file all the text apart from the word 'and', but this code doesn't do that (but I tell it to do that, don't I?). Please help me, where is the bug?

Comment on Extract word Download Code

Replies are listed 'Best First'.
Re: Extract word by ikegami (Patriarch) on Oct 07, 2011 at 17:52 UTC
The first problem is that you do the same thing regardless of the truth of `defined $ignore{$word}`. You could use the following: `perl -pe's/\band\b//g;' in > out` [download] Or maybe you want to skip the entire line: `perl -ne'print if !/\band\b/;' in > out` [download]	[reply] [d/l] [select]
Re: Extract word by suaveant (Parson) on Oct 07, 2011 at 19:05 UTC
You ARE skipping and... but you aren't actually DOING anything when you skip it. You load the WHOLE file into $input_file and match words and then skip, but you aren't removing the word from the file. You'd need a substitute s/// to REMOVE text, something like `s/(\w[\w'-])/$ignore{lc $1} ? '' : $1/g` though you'd probably be better off generating a regular expression that matches any words you want, rather than matching all words and comparing against a hash. There are modules out there to do that, I see Regexp::List, though I think there was another one... That's assuming you just want to remove certain words not the whole line. Edit* Regexp::Assemble is the one I was trying to think of - Ant - Some of my best work - (1 2 3)	[reply] [d/l]
Re: Extract word by Lotus1 (Vicar) on Oct 07, 2011 at 19:22 UTC
`return $sequence; #return the string sequence close IN;` [download] The 'return' statement should come after the close. Otherwise the close statement will never be executed.	[reply] [d/l]