Re: [MacPerl] Random lines from a File

[Chris Nandor <pudge@pobox.com>]

At 12.40 -0500 1999.03.04, Brian McNett wrote:
>This is a very quick & dirty script, which opens a file and prints five
>lines from it at random.  The target file is a list of email addresses in
>this instance, but it could be anything.
>
>#!perl
>
>my $myfile = q(some_file);
>my @data;
>my $length;
>my $i;
>
>open(IN, $myfile) and
>  (@data = <IN>) and
>  close(IN) or
>  die(qq($0: Failed on $myfile: $!\n)); # could use warn()
>
>$length = @data; # Magic! Assigns the length of the array to the scalar!
>
>for ($i = 1; $i <= 5; $i++) {
>  print $data[rand($length - 1)];
>  }
>
>I'm open for any suggestions as to improvements. Can it be made MORE
>random?

Well, here is a slight improvement.  Improvement in that it does not read
the whole file into memory at once.

  #!perl -wl
  my($file, $lines) = 'Shuck Manual';
  open F, $file or die $!;

  for (1..5) {
    print get_random_line();
  }

  sub get_random_line {
    local $.;
    my $line;
    seek(F, 0, 0);
    rand($.) < 1 && (chomp($line = $_)) while <F>;
    return $line;
  }
  __END__

It is an adaptation of the entry in the FAQ and Cookbook.  I don't fully
understand it, so don't ask me.  :)

--
Chris Nandor          mailto:pudge@pobox.com         http://pudge.net/
%PGPKey = ('B76E72AD', [1024, '0824090B CE73CA10  1FF77F13 8180B6B6'])



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