Joining an array of keys to a hash with key value pairs like excel vlookup

问题:

I've got an unsorted array of keys like this:

keys = ["ccc", "ddd", "ggg", "aaa", "bbb"] 

and a hash

hash = {"ddd" => 4, "aaa" => 1, "bbb" => 2, "eee" => 5, "fff" => 6} 

I'd like to join these two data structures to return a hash in the original order of keys to the first keys:

{"ccc" => nil, "ddd" => 4, "ggg" => nil, "aaa" => 1, "bbb" => 2} 

Items NOT in the hash (like "ggg") should return nil. This is analogous to the "v-lookup" function in excel. this is in ruby. Thanks!

回答1:

Cryptic:

Hash[keys.zip(hash.values_at *keys)] 

Or a bit longer, a bit less cryptic:

keys.map.with_object({}) {|key, memo| memo[key] = hash[key]} 

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