Ruby:尊重最高版本的独特哈希数组

Question

我正在尝试创建一个具有唯一值的新哈希数组，并尊重重复哈希的最高版本。哈希如下所示:

old_hash = [
{"dependency"=>"websocket", "version"=>"2.8.0", "repo"=>"repo1"},
{"dependency"=>"rails", "version"=>"6.2.0", "repo"=>"repo2"},
{"dependency"=>"httparty", "version"=>"6.0.3.5", "repo"=>"repo2"},
{"dependency"=>"httparty", "version"=>"6.1.0.2", "repo"=>"repo2"},
{"dependency"=>"httparty", "version"=>"6.1.3.2", "repo"=>"repo2"},
{"dependency"=>"rails", "version"=>"6.1.0", "repo"=>"repo3"},
{"dependency"=>"metasploit", "version"=>"2.8.0", "repo"=>"repo3"}
]

如您所见，第三个、第四个和第五个哈希值具有相同的键dependency 值，即httparty 和repo这是 repo2，但第五个哈希具有这三个哈希中的最高版本。因此，我想创建一个具有第一个、第二个、第五个、第六个和第七个哈希的唯一哈希。所以我想要的结果应该是这样的:

unique_hash = [
{"dependency"=>"websocket", "version"=>"2.8.0", "repo"=>"repo1"},
{"dependency"=>"rails", "version"=>"6.2.0", "repo"=>"repo2"},
{"dependency"=>"httparty", "version"=>"6.1.3.2", "repo"=>"repo2"},
{"dependency"=>"rails", "version"=>"6.1.0", "repo"=>"repo3"},
{"dependency"=>"metasploit", "version"=>"2.8.0", "repo"=>"repo3"}
]

关于版本比较，我想用这个方法来比较一下:

def version_greater? (version1, version2)
  Gem::Version.new(version1) > Gem::Version.new(version2)
end

如果版本 1 大于版本 2，则返回 true。

如果有任何有助于解决此问题的建议，我将不胜感激。

Answer 1

一种方法是使用 Hash#update 的形式(又名 merge!)，需要一个 block (这里 { |_,o,n| n["version"] > o["version"] ? n : o }) 确定正在合并的两个哈希中存在的键的值。

old_hash = [
  {"dependency"=>"websocket",  "version"=>"2.8.0",   "repo"=>"repo1"},
  {"dependency"=>"rails",      "version"=>"6.2.0",   "repo"=>"repo2"},
  {"dependency"=>"httparty",   "version"=>"6.0.3.5", "repo"=>"repo2"},
  {"dependency"=>"httparty",   "version"=>"6.1.0.2", "repo"=>"repo2"},
  {"dependency"=>"httparty",   "version"=>"6.1.3.2", "repo"=>"repo2"},
  {"dependency"=>"rails",      "version"=>"6.1.0",   "repo"=>"repo3"},
  {"dependency"=>"metasploit", "version"=>"2.8.0",   "repo"=>"repo3"},
  {"dependency"=>"rails",      "version"=>"6.1.9",   "repo"=>"repo2"}
]

请注意，我已将哈希添加到问题中显示的 old_hash 中。 (顺便说一句，“old_hash”可能不是数组的最佳名称。)

old_hash.each_with_object({}) do |g,h|
  h.update([g["dependency"],g["repo"]]=>g) do |_,o,n|
    n["version"] > o["version"] ? n : o
  end
end.values
  #=> [{"dependency"=>"websocket",  "version"=>"2.8.0",   "repo"=>"repo1"},
  #    {"dependency"=>"rails",      "version"=>"6.2.0",   "repo"=>"repo2"},
  #    {"dependency"=>"httparty",   "version"=>"6.1.3.2", "repo"=>"repo2"},
  #    {"dependency"=>"rails",      "version"=>"6.1.0",   "repo"=>"repo3"},  
  #    {"dependency"=>"metasploit", "version"=>"2.8.0",   "repo"=>"repo3"}]

---

值的接收者可以看出如下。

  {["websocket", "repo1"] =>{"dependency"=>"websocket",  "version"=>  "2.8.0", "repo"=>"repo1"},
   ["rails", "repo2"]     =>{"dependency"=>"rails",      "version"=>  "6.2.0", "repo"=>"repo2"},
   ["httparty", "repo2"]  =>{"dependency"=>"httparty",   "version"=>"6.1.3.2", "repo"=>"repo2"},
   ["rails", "repo3"]     =>{"dependency"=>"rails",      "version"=>  "6.1.0", "repo"=>"repo3"},
   ["metasploit", "repo3"]=>{"dependency"=>"metasploit", "version"=>  "2.8.0", "repo"=>"repo3"}}

请参阅文档以获取三个 block 变量的描述:_(公共(public)键，此处使用下划线表示它未在 block 计算中使用)、o，正在构建的哈希中的公共(public) key 的值(认为是“旧”)，以及 n，正在合并的哈希中的公共(public) key 的值(认为是"new")。