ruby-on-rails - 使用 Ruby 计算散列字母的数量？

Question

我在计算带有散列的字母时遇到了这个问题:

#Counting with hashes!
#Experiment by writing a couple of short programs that will use Hashes to count 
#objects by incrementing a key value.
#Write a funcition that will count the number of letters in a phrase.
#Example "cat in the hat"  -> return:  {"t"=>3, "h"=>2, "a"=>2, "i"=>1, "n"=>1, "e"=>1, "c"=>1}
#From descending order.  Largest to smallest.  Do not include spaces.

这是我的解决方案:

def count_letters(str)
  count = Hash.new(0)
  str.delete(" ").each_char { |letter|  count[letter]+=1}  
  Hash[count.sort_by {|k,v| v}.reverse]
end

print count_letters("cat in the hat")

为了让我按降序对它进行排序，我不得不放置这段代码:

Hash[count.sort_by {|k,v| v}.reverse]

我还能做什么折射？还有其他方法可以进行降序排序吗？

有更好的方法吗？

Answer 1

你可以通过 -v 排序来避免反转

def count_letters(str)
  counts = str.delete(' ').each_char.inject(Hash.new(0)) {|a,c| a[c] += 1; a}
  Hash[counts.sort_by {|_,v| -v}]
end