在 Perl 中，如何生成列表的所有可能组合? [英] In Perl, how can I generate all possible combinations of a list?

问题描述

我有一个带有列表的文件，并且需要制作一个将每一行与另一行进行比较的文件.例如，我的文件有这个:

I have a file with a list, and a need to make a file that compares each line to the other. for example, my file has this:

AAA  
BBB  
CCC  
DDD  
EEE

我希望最终列表如下所示:

I would like the final list to look like this:

AAA  BBB  
AAA  CCC  
AAA  DDD  
AAA  EEE  
BBB  CCC  
BBB  DDD  
BBB  EEE  
CCC  DDD  
CCC  EEE  
DDD  EEE

我第一次尝试在 Perl 中执行此操作，但遇到了一些麻烦.我知道你需要创建一个数组，然后拆分它，但之后我遇到了一些麻烦.

I am trying to do this in Perl, for this first time and am having a little trouble. I do know that you need to make an array, and then split it, but after that I am having some trouble.

推荐答案

使用 Algorithm::Combinatorics.基于迭代器的方法比一次性生成所有内容更可取.

Use Algorithm::Combinatorics. The iterator based approach is preferable to generating everything at once.

#!/usr/bin/env perl

use strict; use warnings;
use Algorithm::Combinatorics qw(combinations);

my $strings = [qw(AAA BBB CCC DDD EEE)];

my $iter = combinations($strings, 2);

while (my $c = $iter->next) {
    print "@$c\n";
}

输出:

AAA BBB
AAA CCC
AAA DDD
AAA EEE
BBB CCC
BBB DDD
BBB EEE
CCC DDD
CCC EEE
DDD EEE

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