perl 不放回抽样

好吧，上次由于交代不是很清楚，搞了个抽样放回的程序，今天重新弄了一下，把它写成模块的形式：

package Sampling;
use warnings;
use strict;

require Exporter;
our @ISA = qw(Exporter);
our @EXPORT_OK = qw(swor fac); #swor -- sampling without replacement

sub swor{
	my ($sample_num,$sampling_num) = @_;
	my @array = (1..$sample_num);
	my @percom;
	for(my $i = 0; $i < $sampling_num; $i ++)
	{
		my $index = int(rand(@array));
		push @percom,$array[$index];
		my @tmp;
		if($index eq 0)
		{
			@tmp = @array[($index + 1)..$#array];
		}elsif($index eq $#array){
			@tmp = @array[0..($index - 1)];
		}else{
			@tmp = (@array[0..($index - 1)],@array[($index + 1)..$#array]);
		}
		@array = ();
		@array = @tmp;
	}
	return @percom;
}

sub fac{
	my $value = shift;
	if($value eq 1)
	{
		return 1;
	}elsif($value eq 0){
		return 1;
	}else{
		return $value * &fac($value - 1);
	}
}

文件名保存与package相同的名字，后缀为.pm，主程序调用就可以了。