in Ruby, how to extract a key from the Hash having the value -


I thought I'm Ruby huge when I wrote this: 

  # this hash Hash = {'Portugal' = & gt; 1, 'France' = & gt; 2, 'USA' = & gt; 3} # country_id input comes from country_name =. (Hash .select {| k, v | v == country_id.to_i} .first || []). First   
 This is to be removed in the right way, the country's name and if the country is not found then it does not fail.  
 I am completely happy with it.  
 Although my tutor says that according to readability it can be customized, length and performance!  
 What can be more clear / sharp than this?  
 Please give advice   
 
 
 OK, it seems that your tutor is right :)  
 You can do this:  
  hash.invert [country_id.to_i] # will work on all editions   
 Or, as suggested by @littlecegian  
  hash (country_id.to_i) will work on # 1.9   
 or, as is done by @steenslag Recommended  
  hash.index (country_id.to_i) will work on # 1.8 and 1.9, with a warning on 1.9  with / past> 
 full example:  
  hash = {'Portugal' = & gt; 1, 'France' = & gt; 2, 'USA' = & gt; 3}% w [2 3 1 Bla]. Country_id | # All versions country_name = hash.invert [country_id.to_i] # 1.9 only country_name = hash.key (country_id.to_i) # 1.8 and 1.9, 1.9 country_name with a warning = hash.index (country_id.to_i) printf "country_id =% S, country_name =% s \ n ", country_id, country_name end   
 will print:  
  country_id = 2, country_name = France country_id = 3 , Country_name = USA country_ id = 1, country_name = Portugal country_ id = blah, country_name =   
 see it running

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