根据Ruby中的公共键值创建新的哈希值

Question

假设我在Ruby中有一个看起来像这样的哈希:

{ :ie0 => "Hi",    :ex0 => "Hey",       :eg0 => "Howdy", 
  :ie1 => "Hello", :ex1 => "Greetings", :eg1 => "Good day"}

有什么好办法把它变成这样的东西:

{ "0" => 
    { 
        "ie" => "Hi", "ex" => "Hey", "eg" => "Howdy"
    },
  "1" => 
    {
        "ie" => "Hello", "ex" => "Greetings", "eg" => "Good day"
    }
}

Answer 1

您要求一种好的方法来做到这一点，所以答案是：一种您或同事从现在起六个月后可以理解和维护的方法。

首先，您需要一个具有自动生存功能的哈希，因为您正在创建一个嵌套哈希结构。这是一种非常有用的编码模式，可以简化您的应用程序代码：

# Copied & pasted from the question
old_hash = { :ie0 => "Hi", :ex0 => "Hey", :eg0 => "Howdy", :ie1 => "Hello", :ex1 => "Greetings", :eg1 => "Good day"}

# Auto-vivify
new_hash = Hash.new { |h, k| h[k] = { } }

然后，您可以以这种简单的方式循环遍历现有的键，分解每个键的各个部分，并使用它们将值保存在新的哈希中：

old_hash.each_pair do |key, value|
  key =~ /^(..)(.)$/               # Make a regex group for each string to parse
  new_hash[$2][$1] = value         # The regex groups become the new hash keys
end

puts new_hash

我得到这个输出：

{"0"=>{"ie"=>"Hi", "ex"=>"Hey", "eg"=>"Howdy"}, "1"=>{"ie"=>"Hello", "ex"=>"Greetings", "eg"=>"Good day"}}