ruby array hash get key by value and value by key

Question

我有散列{ "1" => "one", "2" => "two", "3" => "three" }

如何按值取键和按键取值

如果我通过“1”，我得到 "one"，如果我通过 "two"，我得到“2”

def finder (string)
  table = { "1" => "one", "2"   =>  "two", "3"  =>  "three" }
  *magick*
  }
  return string
end
puts finder("1") => one
puts finder("one") => 1

Answer 1

Hash#key returns 给定值的键：

@hash = {"1"=>"one", "2"=>"two", "3"=>"three"}
@hash.key("one") #=> "1"

或 nil 如果不存在这样的值：

@hash.key("four") #=> nil

要获取键的值或值的键，您可以使用：

def finder(str)
  @hash[str] || @hash.key(str)
end

finder("1")   #=> "one"
finder("one") #=> "1"

Answer 2

如果您的散列很大并且您将重复执行此操作，您可以创建一个新的散列以进行快速查找：

h = {"1"=>"one", "2"=>"two", "3"=>"three"}
nh = h.merge h.invert
  #=> {"1"=>"one", "2"=>"two", "3"=>"three", "one"=>"1", "two"=>"2", "three"=>"3"}

ruby array hash get key by value and value by key

ruby array hash get key by value and value by key

ruby

arrays

reverse