Ruby - 如何删除哈希数组中的重复项？

I have an array of hashes within an array of hashes. I'd like to remove duplicates based on the values of the inner arrays.

我在哈希数组中有一个哈希数组。我想根据内部数组的值删除重复项。

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

You can see above that the phrases defense, companies, and Symantec each contain identical arrays. How can I keep only the first hash that contains one of the identical arrays?

您可以在上面看到,防御,公司和Symantec的短语都包含相同的数组。如何只保留包含其中一个相同数组的第一个哈希?

Expected output:

{"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"}]}

Note: in the above example each inner array of "phrases" only contains one hash, but in the application it could contain several posts.

注意:在上面的例子中,“短语”的每个内部数组只包含一个哈希,但在应用程序中它可以包含几个帖子。

3 个解决方案

#1

topics.invert.invert will reduce the hash to a single (arbitrarily-chosen) key for each unique value.

topics.invert.invert会将哈希值减少为每个唯一值的单个(任意选择)键。

#2

With this solution you get only the array:

使用此解决方案,您只获得数组:

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

It returns just:

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"}]

#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"}]}]

See Array#uniq for the case when uniq employs a block. Note the sentence, "self is traversed in order, and the first occurrence is kept."

有关uniq使用块的情况,请参阅Array #uniq。请注意句子“按顺序遍历自我,并保留第一次出现”。

#1