perl - 按值和键对哈希进行排序(按顺序)

Question

我正在寻找一种好方法，在 Perl 中先按值排序，然后再按键排序。

示例:

 my %userids = (
  williams => "Marketing",
  smith    => "Research",
  johnson  => "Research",
  jones    => "Marketing",
  brown    => "Marketing",
  davis    => "Research"
);

输出:

Marketing: brown
Marketing: jones
Marketing: williams
Research: davis
Research: johnson
Research: smith

请注意，值是第一个排序级别。第二个排序级别是键。知道如何以优雅且高性能的方式做到这一点吗？谢谢!

Answer 1

很好的引用:http://www.misc-perl-info.com/perl-sort.html#shv

#!/usr/bin/perl

my %userids = (
    williams => "Marketing",
    smith    => "Research",
    johnson  => "Research",
    jones    => "Marketing",
    brown    => "Marketing",
    davis    => "Research"
);

foreach (sort { ($userids{$a} cmp $userids{$b}) || ($a cmp $b) } keys %userids) 
{
    print "$_: $userids{$_}\n";
}