Ruby重构哈希循环方法返回

Question

I have code like thus (and I often run into this sort of method signature, the noob that I am coming from java):

  def totals
    t = 0
    @data.each do |k, v|
      t += v['totals'].to_i
    end
    t
  end

@data is a hash of hashes, each internal hash value has a totals key. As you can see, I am summing up all the totals.

Could this be simplified or programmed in a different style (I am sure! This is RUBY afterall)? Why do I need to instantiate t ? Couldn't I return t directly from the each loop without a last conditional?

It just does not feel clean! OH wait! I just remembered blocks , but I'll wait for your answers ...

UPDATE:

The data structure is as such:

{ typeA: { items: [], totals: "10" },  typeB: { items: [], totals: "23" }}

I am using Rails! So Rails specific functions would also be great if they extend beyond the vanilla Ruby stack!

Answer 1

Since you've indicated that you are using Ruby on Rails, you can take advantage of Active Support's Enumerable#sum method:

def totals
  @data.sum {|_,v| v['totals'].to_i }
end

Answer 2

Use inject :

def totals
  @data.inject(0) do |t, (_, v)|
    t + v['totals'].to_i
  end
end

Answer 3

Use Enumerable sum

def totals
  @data.sum { |_,v| v['totals'].to_i }
end

You can also have start value different from 0

def totals(start_value= 0)
  @data.sum(start_value) { |_,v| v['totals'].to_i }
end

Answer 4

在Rails 5中，您可以利用Enumerable#pluck优势

h.values.pluck(:totals).map(&:to_i).sum

Answer 5

@data.map{ |_, v| v['totals'].to_i }.inject(:+)

甚至更短：

@data.map{ |_, v| v['totals'].to_i }.sum