反向散列紅寶石

Question

給定一個哈希這樣的：

{ "key_1" => ["value1","value2","value3"], "key_2" => ["value4","value5"], ...} 

我怎樣才能得到一個哈希這樣的：

{ "value1" => "key_1", "value2" => "key_1", "value3" => "key_1", "value4" => "key_2", "value5" => "key_2" } 

我已經試過這樣：

Hash[original_hash.flat_map { |key, values| original_hash.map { |value| [value, key] } }] 

Answer 1

hash.each_with_object({}) { |(key,values),h| values.each { |v| h[v] = key } } 

Answer 2

只是想迭代在散列像正常：

h = { "key_1" => ["value1","value2","value3"], "key_2" => ["value4","value5"]} 
newh = {} 
h.each do |key, vals| 
    vals.each { |v| newh[v] = key } 
end 

p newh 
#=> {"value1"=>"key_1", "value2"=>"key_1", "value3"=>"key_1", "value4"=>"key_2", "value5"=>"key_2"} 

Answer 3

鑑於此哈希：

> h = { "key_1" => ["value1","value2","value3"], "key_2" => ["value4","value5"]} 
=> {"key_1"=>["value1", "value2", "value3"], "key_2"=>["value4", "value5"]} 

你可以這樣做：

> h.map{ |k, v| v.map{ |f| { f => k }}}.flatten 
=> [{"value1"=>"key_1"}, {"value2"=>"key_1"}, {"value3"=>"key_1"}, {"value4"=>"key_2"}, {"value5"=>"key_2"}] 

更新答案：

> h.inject({}){ |h, (k,v)| v.each{ |f| h[f] = k }; h } 
=> {"value1"=>"key_1", "value2"=>"key_1", "value3"=>"key_1", "value4"=>"key_2", "value5"=>"key_2"} 

Answer 4

鑑於你的哈希：

Hash = { "key_1" => ["value1","value2","value3"], "key_2" => ["value4","value5"]} 

我把你的散列稱爲「哈希」，這樣我們就可以反轉它。反轉散列會切換鍵和值對。

Hash ={ "key_1" => ["value1","value2","value3"], "key_2" => ["value4","value5"]} 

inverseHash = Hash.invert 

所以，我叫倒轉了，「inverseHash」。如果你提出，這inverseHash，你會得到你的結果：

puts inverseHash 

上面的代碼輸出：

{["value1", "value2", "value3"]=>"key_1", ["value4", "value5"]=>"key_2"}