What is the most efficient way to sort hashes in ruby? -

i trying sort 20 hashes in ruby based on 1 of attributes of array. want return top 3 hash keys, don't want have compare each one.

here example below of similar trying sort. want sort based on powerrank.

["green", {:price=>24.88, :numreviews=>822, :avgstarsrank=>41.0, :reviewsrank=>28, :powerrank=>73.976}]  ["steve", {:price=>14.96, :numreviews=>3, :avgstarsrank=>40.0, :reviewsrank=>0, :powerrank=>42.992000000000004}]  ["joey", {:price=>40.27, :numreviews=>814, :avgstarsrank=>44.0, :reviewsrank=>28, :powerrank=>80.054}]  ["board", {:price=>14.96, :numreviews=>3, :avgstarsrank=>40.0, :reviewsrank=>0, :powerrank=>47}]  ["john", {:price=>40.27, :numreviews=>814, :avgstarsrank=>44.0, :reviewsrank=>28, :powerrank=>16}] 

for this, want array ["joey", "green", "board"]. suggestions on how tackle issue?

edit: here example in original hash form:

powerrankings =     {         "green"=>{:price=>24.88, :numreviews=>822, :avgstarsrank=>41.0, :reviewsrank=>28, :powerrank=>73.976},          "steve"=>{:price=>14.96, :numreviews=>3, :avgstarsrank=>40.0, :reviewsrank=>0, :powerrank=>42.992000000000004},          "joey"=>{:price=>40.27, :numreviews=>814, :avgstarsrank=>44.0, :reviewsrank=>28, :powerrank=>80.054}}         "board"=>{:price=>14.96, :numreviews=>3, :avgstarsrank=>40.0, :reviewsrank=>0, :powerrank=>47},          "john"=>{:price=>40.27, :numreviews=>814, :avgstarsrank=>44.0, :reviewsrank=>28, :powerrank=>16}     } 

assuming powerrankings not showed rather,

powerrankings = {   "green" => {:price=>24.88, :numreviews=>822, :avgstarsrank=>41.0, :reviewsrank=>28, :powerrank=>73.976},    "steve" => {:price=>14.96, :numreviews=>3, :avgstarsrank=>40.0, :reviewsrank=>0, :powerrank=>42.992000000000004},    "joey" => {:price=>40.27, :numreviews=>814, :avgstarsrank=>44.0, :reviewsrank=>28, :powerrank=>80.054},   "board" => {:price=>14.96, :numreviews=>3, :avgstarsrank=>40.0, :reviewsrank=>0, :powerrank=>47},    "john" => {:price=>40.27, :numreviews=>814, :avgstarsrank=>44.0, :reviewsrank=>28, :powerrank=>16} } 

then,

powerrankings.sort_by{|_, h| h[:powerrank]}.reverse.first(3).map(&:first) # => ["joey", "green", "board"]