print out the values from a hash

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

I am still struggling a bit with hashes. I want to count the number of strings of the form, "FREQ <val>" in a set of files. I can see that in fact I did count the strings, just not sure how to print the results.

  use strict;
  use warnings;
  use Env;
  use integer;
  use Data::Dumper;

  my(
    %cnt,
    $file,
    @files,
    $key,
    $line,
  );


  @files = <*.abc>;

  foreach $file (@files) {

    open   (FILE, "$file");

    my @contents=<FILE>;
    close FILE; 

    my @freqs = grep(/ FREQ /,@contents);

    foreach $line (@freqs) {

      $line =~ s/ is begin.*//;
      $line =~ s/.* FREQ/FREQ/;
      #print "$file $line";
      chomp($line);

      # start counting

      if (defined $cnt{$line}) {
        $cnt{$line}{c} = $cnt{$line}{c} + 1;
      }
      else {
        $cnt{$line}{c} = 1;
        $cnt{$line}{val} = $line;
        $cnt{$line}{file} = $file;
      }

    }

    # Print out results per file, all the found FREQs:

    # ( Definitely where I get it wrong starts here )

    for $key ( keys %($cnt->{file}) ) {

      print "key $key \n";

    }   

  }
[download]

The intended results should be something like the following:

file1.abc  FREQ 12.3 5
file1.abc  FREQ 5    2
file2.abc  FREQ 33.3 12
[download]

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Re: print out the values from a hash by choroba (Cardinal) on Jan 11, 2013 at 17:52 UTC
This is how I would do it. The main changes were: Do not declare variables in a wider scope than needed. Use lexical filehandles and 3-argument open with `or die`. If you want to output frequencies per file, you have to store them per file. That's why the first key is the filename. The line is already in the key, no need to store it again to a value. You do not have to initialize the counting hash. Just increment it. `#!/usr/bin/perl use warnings; use strict; my %cnt; for my $file (glob '.abc') { open my $FILE, '<', "$file" or die "$!"; for my $line (grep / FREQ /, <$FILE>) { $line =~ s/ is begin.//; $line =~ s/.* FREQ/FREQ/; chomp($line); $cnt{$file}{$line}++; } } for my $file ( keys %cnt) { for my $line ( keys %{ $cnt{$file} } ) { print "$file $line $cnt{$file}{$line}\n"; } }` [download] لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ	[reply] [d/l] [select]
Re: print out the values from a hash by Kenosis (Priest) on Jan 11, 2013 at 18:11 UTC
choroba has provided excellent suggestions. Here an option that uses a hash of arrays (HoA), where the key is the file name and its associated value is a reference to a list of frequencies: `use strict; use warnings; my %files; for my $file (<*.abc>) { open my $fh, '<', $file or die $!; while (<$fh>) { push @{ $files{$file} }, $1 if /FREQ\s+([\d.]+)/; } close $fh; } print "$_ FREQ @{ $files{$_} }\n" for keys %files;` [download] Output on files containing FREQ <val> info: `file3.abc FREQ 27.047 400 file1.abc FREQ 33.3 2.22 file2.abc FREQ 12345.67` [download] Hope this helps!	[reply] [d/l] [select]