通过ruby中的多维哈希进行迭代

Question

groceries=[{"bread"=>"2", "eggs"=>"3", "cheese"=>"1", "butter"=>"4"}, 
      {"juice"=>"3", "milk"=>"1", "tea"=>"1", "sugar"=>"1"}] 

如何迭代每个散列并将其推入单独的数组？ 我想要的东西，看起来像这样：

items = [["bread","eggs","cheese","butter"],["juice","milk","tea","sugar"]] 

Answer 1

试试这个

groceries.map(&:keys) 
=> [["bread", "eggs", "cheese", "butter"], ["juice", "milk", "tea", "sugar"]] 

Answer 2

如果你只是想有5个或更多字符的按键：

p groceries.map{ |hash| hash.keys.select{ |key| key.length >= 5 } } 
#=> [["bread", "cheese", "butter"], ["juice", "sugar"]] 

如果您只需要最多2个具有5个或更多字符的键：

p groceries.map{ |hash| hash.keys.select{ |key| key.length >= 5 }.first(2) } 
#=> [["bread", "cheese"], ["juice", "sugar"]]