Ruby - 如何刪除哈希數組中的重復項？

Question

我在哈希數組中有一系列哈希。 我想根據內部數組的值刪除重復項。

topics = [{"defense"=>
   [{:id=>30,
     :source=>"Hacker News",
     :title=>
      "China-based campaign breached satellite, defense companies: Symantec",
     :link=>
      "https://www.reuters.com/article/us-china-usa-cyber/china-based-campaign-breached-satellite-defense-companies-symantec-idUSKBN1JF2X0"}]},
 {"companies"=>
   [{:id=>30,
     :source=>"Hacker News",
     :title=>
      "China-based campaign breached satellite, defense companies: Symantec",
     :link=>
      "https://www.reuters.com/article/us-china-usa-cyber/china-based-campaign-breached-satellite-defense-companies-symantec-idUSKBN1JF2X0"}]},
 {"Symantec"=>
   [{:id=>30,
     :source=>"Hacker News",
     :title=>
      "China-based campaign breached satellite, defense companies: Symantec",
     :link=>
      "https://www.reuters.com/article/us-china-usa-cyber/china-based-campaign-breached-satellite-defense-companies-symantec-idUSKBN1JF2X0"}]}]

topics.uniq { |phrase, post| post }
puts topics

您可以在上面看到， defense ， companies和Symantec的短語都包含相同的數組。 如何只保留包含其中一個相同數組的第一個哈希？

預期產量：

{"defense"=>
  [{:id=>30,
    :source=>"Hacker News",
    :title=>
     "China-based campaign breached satellite, defense companies: Symantec",
    :link=>
     "https://www.reuters.com/article/us-china-usa-cyber/china-based-campaign-breached-satellite-defense-companies-symantec-idUSKBN1JF2X0"}]}

注意：在上面的例子中，“短語”的每個內部數組只包含一個哈希，但在應用程序中它可以包含幾個帖子。

Answer 1

topics.invert.invert會將哈希值減少為每個唯一值的單個（任意選擇）鍵。

Answer 2

使用此解決方案，您只獲得數組：

topics.map { |topic| topic.values }.uniq.flatten 

它只返回：

# => [{:id=>30, :source=>"Hacker News", :title=>"China-based campaign breached satellite, defense companies: Symantec", :link=>"https://www.reuters.com/article/us-china-usa-cyber/china-based-campaign-breached-satellite-defense-companies-symantec-idUSKBN1JF2X0"}]

Answer 3

topics = [
  { "defense"   => [{ id: 30, source: "Hacker", title: "China", link: "F2X0"}] },
  { "companies" => [{ id: 30, source: "Hacker", title: "China", link: "F2X0"}] },
  { "Symantec"  => [{ id: 30, source: "Hacker", title: "China", link: "F2X0"}] }
]

topics.uniq { |h| h.values }
  #=> [{"defense"=>[{:id=>30, :source=>"Hacker", :title=>"China", :link=>"F2X0"}]}]

有關uniq使用塊的情況，請參閱Array #uniq 。 請注意句子“ self按順序遍歷，並且第一次出現”。