Adding hashes from an array

Question

I am trying to create an array / hash from an array of several hashes with the same keys and average values. My array:

[{:amount=>897500, :gross_amount=>897500, :tax=>147500, :hotel_fees=>0, :base_fare=>750000, :currency=>"INR"}, {:amount=>1006500, :gross_amount=>1006500, :tax=>156500, :hotel_fees=>0, :base_fare=>850000, :currency=>"INR"}]

Now I want to return something like this:

{:amount=>952000, :gross_amount=>952000, :tax=>152000, :hotel_fees=>0, :base_fare=>800000, :currency=>"INR"}

where values ​​is the average of each hash with the same key.

Is there an easy way to do this. I tried using merge, but the currency is getting 0 with it.

My attempt:

p[0].merge(p[1]){|k,v1,v2| (v1+v2)/2 unless v1 && v2 == "INR"}

Edit:

In fact, my problem did not end here, so after getting the average value, I needed to insert the values ​​inside another hash. So I used something like this:

        price_array = offer_values.map do |v| 
          v.inject do |k, v| 
            k.merge!(price: k[:price].merge(v[:price]){|_, a, b| [a, b].flatten })
          end
        end
        price_array.map do |o|
          o[:price] = {}.tap{ |h| o[:price].each {|k, list| h[k] = list.all?{|e| [Fixnum, NilClass].include? e.class} ? list.map(&:to_i).sum/list.size : list.compact.first ; h  } }
        end

Where offer_array is the one that has my own / first array in separate hashes. I tried this with 2 and 3 hashes, and it works.

If you have suggestions for improving the code, it is open.

Answer 1

inject merge, , currency Fixnum, , "INR" :

array = [
  {:amount=>897500,  :gross_amount=>897500,  :tax=>147500, :hotel_fees=>0, :base_fare=>750000, :currency=>"INR"}, 
  {:amount=>1006500, :gross_amount=>1006500, :tax=>156500, :hotel_fees=>0, :base_fare=>850000, :currency=>"INR"}
]

p array.inject{|k,v| k.merge(v){|_,a,b| [a,b].all?{|e| e.is_a?(Fixnum)} ? (a+b)/2 : b}}
# => {:amount=>952000, :gross_amount=>952000, :tax=>152000, :hotel_fees=>0, :base_fare=>800000, :currency=>"INR"}

:

main_array = [
  {:amount=>897500,  :gross_amount=>897500,  :tax=>147500, :hotel_fees=>0, :base_fare=>750000, :currency=>"INR"}, 
  {:amount=>1006500, :gross_amount=>1006500, :tax=>156500, :hotel_fees=>0, :base_fare=>850000, :currency=>"INR"},
  {:amount=>1006500, :gross_amount=>1006500, :tax=>156500, :hotel_fees=>0, :base_fare=>850000, :currency=>"INR"},
]
array_result = main_array.flat_map(&:to_a).group_by(&:first).map do |key, array| 
  { 
    key => (
      result = array.inject(0) do |total, (_, value)| 
        value.is_a?(Fixnum) ? total + value : value
      end 
      result.is_a?(Fixnum) ? result / main_array.size : result 
    ) 
  } 
end
p array_result

Answer 2

IRB

2.2.3 :011 > b = {test1: 30, test2: 40}
 => {:test1=>30, :test2=>40} 
2.2.3 :012 > a = {test1: 20, test2: 60}
 => {:test1=>20, :test2=>60} 
2.2.3 :013 > c = a.merge(b){|key, oldval, newval| (newval + oldval)/2}
 => {:test1=>25, :test2=>50} 

Answer 3

The accepted answer will not work for more than 2 hashes, since mergeonly 2 by 2 works, and you calculate the average value here.

(((3 + 2) / 2) + 2.5) / 2 is different from (3 + 2 + 2.5) / 3

So I wrote a code snippet that could do what you want for any size of array you have

  def self.merge_all_and_average(array)
    new_hash = {}
    unless array.empty?
      array[0].keys.each do |key|
        if array[0][key].class == Fixnum
          total = array.map { |i| i[key] }.inject(0) { |sum, x| sum + x }
          new_hash = new_hash.merge(key => total / array.size)
        else
          new_hash = new_hash.merge(key => array[0][key])
        end
      end
    end
    new_hash
  end

Answer 4

This should work with any number of hashes:

data = [
  { amount: 897_500, gross_amount: 897_500, tax: 147_500, hotel_fees: 0, base_fare: 750_000, currency: 'INR' },
  { amount: 1_006_500, gross_amount: 1_006_500, tax: 156_500, hotel_fees: 0, base_fare: 850_000, currency: 'INR' },
  { amount: 1_006_500, gross_amount: 1_006_500, tax: 156_500, hotel_fees: 0, base_fare: 850_000, currency: 'INR' }
]

transposed_hashes = data.each_with_object(Hash.new{|h, k| h[k] = []}) do |h, mem|
  h.each do |k, v|
    mem[k] << v
  end
end
# {:amount=>[897500, 1006500, 1006500], :gross_amount=>[897500, 1006500, 1006500], :tax=>[147500, 156500, 156500], :hotel_fees=>[0, 0, 0], :base_fare=>[750000, 850000, 850000], :currency=>["INR", "INR", "INR"]}

average_hash = transposed_hashes.map do |k, v|
  new_value = if v[0].is_a? Integer
                v.sum.to_f / v.size
              else
                v[0]
              end
  [k, new_value]
end.to_h

puts average_hash
# {:amount=>970166.6666666666, :gross_amount=>970166.6666666666, :tax=>153500.0, :hotel_fees=>0.0, :base_fare=>816666.6666666666, :currency=>"INR"}