计算Ruby中的哈希值

我有一个Ruby中的哈希数组，如下所示：

domains = [
  { "country" => "Germany"},
  {"country" => "United Kingdom"},
  {"country" => "Hungary"},
  {"country" => "United States"},
  {"country" => "France"},
  {"country" => "Germany"},
  {"country" => "Slovakia"},
  {"country" => "Hungary"},
  {"country" => "United States"},
  {"country" => "Norway"},
  {"country" => "Germany"},
  {"country" => "United Kingdom"},
  {"country" => "Hungary"},
  {"country" => "United States"},
  {"country" => "Norway"}
]

counted = {
  "Germany" => "3",
  "United Kingdom" => "United Kingdom",
  "Hungary" => "3",
  "United States" => "4",
  "France" => "1"
}

从这个散列数组中，我想创建一个新的散列，如下所示：

domains = [
  { "country" => "Germany"},
  {"country" => "United Kingdom"},
  {"country" => "Hungary"},
  {"country" => "United States"},
  {"country" => "France"},
  {"country" => "Germany"},
  {"country" => "Slovakia"},
  {"country" => "Hungary"},
  {"country" => "United States"},
  {"country" => "Norway"},
  {"country" => "Germany"},
  {"country" => "United Kingdom"},
  {"country" => "Hungary"},
  {"country" => "United States"},
  {"country" => "Norway"}
]

counted = {
  "Germany" => "3",
  "United Kingdom" => "United Kingdom",
  "Hungary" => "3",
  "United States" => "4",
  "France" => "1"
}

使用Ruby 1.9有没有一种简单的方法可以做到这一点？

这个怎么样

counted = Hash.new(0)
domains.each { |h| counted[h["country"]] += 1 }
counted = Hash[counted.map {|k,v| [k,v.to_s] }]

---

此哈希具有冲突键。该哈希看起来不像您希望的那样。哈希中只能有一个具有给定密钥的条目，因此您只能有一个条目（我认为保证是

“country”=>“Norway”

。您想要数组的答案吗？除了源哈希的问题之外。您希望

“United Kingdom”=>“United Kingdom”

还是

“United Kingdom”=>2

？“我在Ruby中有一个哈希，看起来像这样…”不，你没有！-）对不起，我编辑了我的问题-它应该是一个哈希数组！太好了！-你是一个救命恩人。我花了很多时间试图让它工作！！谢谢！如果，我有不同的键怎么办。例如-这是我的哈希，哈希={a:5，b:2，c:3，d:5}.我想要这样的结果-value\u count（散列，2）=>1，value\u count（散列，5）=>2，其中value\u count（散列，值）这是我的方法。当一个国家有9个以上的实例时会发生什么情况？：）谢谢，我没想到。：）我应该在评论之前阅读手册。不客气，从实例中学习比从手册中学习更好