Question

I have an array of questions where each question has a category_id and a value.

I’d like to map these so that when the key (category_id) already exists in the hash, then the values are added together.

And, finally, I’d like to find the largest value in the hash:

h = Hash.new {|k, v| k[v] = 0}  

@test_session.answered_questions.each do |q|

  if h.key?(q.category_id)
     #add q.value to the value stored in the hash
  else
     h = { q.category_id => q.value } #insert the "q.category_id" as key and with value "q.value"
  end        

end

key_with_max_value = h.max_by { |k, v| v }[0] #find the highest value

@result.category = key_with_max_value
@result.score = h[key_with_max_value].value  

There is probably a lot better way to achieve this but I’m quite new to Ruby.

Answer 1

h = Hash.new(0)
@test_session.answered_questions.each {|q| h[q.category_id] += q.value}
@result.category, @result.score = h.max_by { |k, v| v }

Each value in the hash will be initialized to zero with Hash.new(0) and since h.max_by returns the key value pair, you can directly assign them to your @result variable.