I think this method is accurate and fair:
open my $some_filehandle, "<", "quotefile.txt";
my $set_size = 3;
my $set = random_set_of_n($some_filehandle, $set_size);
sub random_set_of_n {
my ($fh, $size) = @_;
my @set;
local ($., $_);
seek $fh, 0, 0;
while (<$fh>) { chomp; push @set, $_; last if @set == $size; }
# XXX: @set *should* be shuffled now if you care about ordering
while (<$fh>) { chomp; $set[rand @set] = $_ if $size/$. > rand; }
return \@set;
}
I think it's a fair distribution. My tests imply it is.
Update: the set
should be shuffled where I've indicated. It's not necessary if you're going to be plucking elements from it at random later on, though, only if you want a randomly ordered list returned.