perl - 按值和键(按此顺序)对哈希进行排序

我正在寻找一种很好的方法，可以按值先按键，然后按键对Perl中的哈希进行排序。

例子:

 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，值是第一排序级别。第二排序级别是关键。知道如何以优雅和高性能的方式执行此操作吗？谢谢!

最佳答案

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";
}