从 Ruby 哈希中转移特定的匹配键值对

Question

我有一个Ruby哈希：

@tags = { "project_status" => { "title" => "Project status" }, 
          "milestones"     => { "title" => "Milestones"},
          "lessons"        => { "title" => "Lessons"}, 
          "tasks"          => { "title" => "Tasks"} }

我想从这个哈希中shift特定的键值对。例如，如果我对"milestones"标签感兴趣，那么哈希shift会给我：

=> ["milestones", {"title"=>"Milestones"}] 

这正是我想要的。

除了我无法弄清楚如何选择特定的键值对。

我可以写一些东西来迭代哈希，直到找到匹配的键，然后调用shift，但我假设有一种更干净的"Ruby 方式"来做到这一点:)

Answer 1

delete可能是

您要查找的。它从哈希中删除相应的键（而shift从数组中删除项目）

tags = { "project_status" => { "title" => "Project status" }, 
          "milestones"     => { "title" => "Milestones"},
          "lessons"        => { "title" => "Lessons"}, 
          "tasks"          => { "title" => "Tasks"} }
def shift hash, key
  [key, hash.delete(key)] # removes key/value pair
  # [key, hash[key]] # leaves key/value pair
end          
shift tags, 'milestones' # => ["milestones", {"title"=>"Milestones"}]
tags # => {"project_status"=>{"title"=>"Project status"}, "lessons"=>{"title"=>"Lessons"}, "tasks"=>{"title"=>"Tasks"}}