Getting the hash key whose value array contains a given string - ruby

Question

I have the following code:
country_code = infer_country # will grab a user's two character country code
region = 'us' # united states by default
region_map = {
"au" => ["au"], # australia
"al" => ["al", "ba", "bg", "hr", "md", "me", "mk", "ro", "si"], # bulgaria and the balkans
"cn" => ["cn"], # china
"ee" => ["ee", "lt", "lv"], # estonia and the baltics
"fi" => ["fi"], # finland
"at" => ["at", "ch", "de"], # germany, austria, switzerland
"cy" => ["cy", "gr", "mt"], # greece, cyprus, malta
"hk" => ["hk"], # hong_kong
"id" => ["id"], # indonesia
"it" => ["it"], # italy
"jp" => ["jp"], # japan
"kp" => ["kp", "kr"], # korea
"ar" => ["ar", "bl", "bo", "br", "bz", "cl", "co", "cr", "cu", "do", "ec", "gf", "gp", "gt", "hn",
"ht", "mf", "mq", "mx", "ni", "pa", "pe", "pr", "py", "sv", "uy", "ve"], # latin america including brazil
"my" => ["my"], # malaysia
"af" => ["af", "eg", "iq", "ir", "sa", "ye", "sy", "il", "jo", "ps", "lb", "om", "kw", "qa", "bh"], # middle east
"nl" => ["nl"], # netherlands
"no" => ["no"], # norway
"pl" => ["pl"], # poland
"pt" => ["pt"], # portugal
"ph" => ["ph"], # philippines
"ru" => ["ru"], # russia
"rs" => ["rs"], # serbia
"sg" => ["sg"], # singapore
"za" => ["za"], # south africa
"bn" => ["bn", "bu", "kh", "la", "tl", "vn"], # south east asia
"es" => ["es"], # spain
"tw" => ["tw"], # taiwan
"th" => ["th"], # thailand
"tr" => ["tr"], # turkey
"gb" => ["gb" ] # united kingdom
}.invert
# version 0.0
region_map.each do |key, value|
if key.include? country_code
region = value
break
end
end
puts region
If country_code is "gb", then "gb" should be printed out. If country_code is in south east asia, say it's "vn", then "bn" should be printed out.
How can I elegantly solve this problem? I can restructure my hash if necessary.

Answer 1

def find_region(country_code)
pair = #region_map.find{|k, v| v.include?(country_code)}
pair && pair.first
end
find_region('gb') # => "gb"
find_region('bz') # => "ar"
find_region('lv') # => "ee"
find_region('ls') # => nil

Answer 2

def find_region(country_code)
#region_map.each {|k,v| return k if v.include? country_code}
nil
end

Answer 3

region_map = Hash.new("us").merge(
"au" => "au",
"al" => "al",
"ba" => "al",
"bg" => "al",
"hr" => "al",
"md" => "al",
"me" => "al",
"mk" => "al",
"ro" => "al",
"si" => "al",
"al" => "al",
"cn" => "cn",
...
)
region_map["non existing code"] # => "us"
region_map[nil] # => "us"
region_map["au"] # => "au"
region_map["ba"] # => "al"
region_map["cn"] # => "cn"
or
def region_map code
case code
when "au"
"au"
when "al", "ba", "bg", "hr", "md", "me", "mk", "ro", "si"
"al"
when "cn"
"cn"
when "ee", "lt", "lv"
"ee"
...
else
"us"
end
end
region_map("non existing code") # => "us"
region_map(nil) # => "us"
region_map("au") # => "au"
region_map("ba") # => "al"
region_map("cn") # => "cn"