From: Dave Thomas <Dave@...>
Date: 2001-10-09T04:58:24+09:00
Subject: [ruby-talk:22259] Re: [Newbie] Switching from Perl : suffling

Damien WYART <damien.wyart@free.fr> writes:

> Dear All,
> 
> Slowly switching from Perl to Ruby, I do not feel very confident with
> what I write in Ruby.
> 
> I would like to get a script to shuffle records from STDIN to STDOUT.
> The Perl version I use is as follows :
> 
> ,----
> | #!/usr/bin/perl
> | 
> | undef $/;
> | $/ = "\n%\n";
> | 
> | sub shuffle {
> |   srand;
> |   my $array = shift;
> |     for (my $i = @$array; --$i > 0; ) {
> |       my $j = int rand ($i+1);
> |       @$array[$i,$j] = @$array[$j,$i];
> |   }
> | }
> | 
> | while (<>) {
> |   push (@lines, $_);
> | }
> | shuffle(\@lines);
> | foreach (@lines) { 
> |   print $_;
> | }
> `----

How about something like

     class Array
       def shuffle
         each_index {|i| o = rand(size); self[i], self[o] = self[o], self[i] }
       end
     end

     original = readlines("\n%\n")

     puts original.shuffle


I'm not sure how good the shuffle itself is, but the principle is
valid :)


Regards


Dave