給定一個數組，返回一個散列

Question

編寫一個給定數組的方法返回一個散列，其中的鍵是數組中的單詞，其值是每個單詞出現的次數。

arr=["A", "man", "a", "plan", "a", "canal","Panama"] 
# => {'a' => 3, 'man' => 1, 'canal' => 1, 'panama' => 1, 'plan' => 1} 

我該如何做到這一點？這裏是我的代碼：

hash={} 
arr.each do |i| 
    hash.each do |c,v| 
     hash[c]=v+1 
    end 
end  

Answer 1

hash = arr.inject({}) do |hash, element| 
    element.downcase! 
    hash[element] ||= 0 
    hash[element] += 1 
    hash 
end 

Answer 2

arr.inject­(Hash.new(­0)){|h,k| k.dow­ncase!; h[k] += 1; h} 

Answer 3

arr = ["A", "man", "a", "plan", "a", "canal","Panama"] 
r = {} 
arr.each { |e| e.downcase!; r[e] = arr.count(e) if r[e].nil? } 

輸出

p r 
#==> {"a"=>3, "man"=>1, "plan"=>1, "canal"=>1, "panama"=>1}