Flatten recursively an hash / array of nested hashes / arrays

flatten_obj.rb

def flatten_obj(obj, keys = [], values = {})
  if obj.is_a?(Array)
    obj.each_with_index do |value, index|
      temp_keys = keys + [index]
      if value.is_a?(Array) || value.is_a?(Hash)
        flatten_obj(value, temp_keys, values)
      else
        values[temp_keys.join('.')] = value
      end
    end
  elsif obj.is_a?(Hash)
    obj.each do |key, value|
      temp_keys = keys + [key]
      if value.is_a?(Array) || value.is_a?(Hash)
        flatten_obj(value, temp_keys, values)
      else
        values[temp_keys.join('.')] = value
      end
    end
  end
  values
end