源码之前，了无秘密，直接上源码：
if(@ARGV!=2){
die "Usage: $0 sample_file sample_number\n";
}
my($sample_file, $sample_number) = @ARGV;
open my $FILE, "<$sample_file" or die "Can't open $sample_file $!\n";
my @content = <$FILE>;
my $all_number = @content;
print STDERR "|$all_number|\n";
my %hits;
my $wl = $sample_number;
for(my $i = 0; $i < $all_number; ++$i){
if(rand($all_number-$i) < $wl){
$hits{$i} = 1;
print STDERR "$wl\n";
--$wl;
}
}
my $j = 0;
print STDERR "start\n";
foreach(@content){
print "$_" if $hits{$j};
++$j;
}
print STDERR "done.\n";
原文:http://blog.csdn.net/hongchangfirst/article/details/25126457
作者:hongchangfirst
hongchangfirst的主页:http://blog.csdn.net/hongchangfirst