I have 2 Arrays.
product_name = ["Pomegranate", "Raspberry", "Miracle fruit", "Raspberry"]
product_quantity = [2, 4, 5, 5]
I'd like to know how to initialize a hash such that it becomes
product_hash = {"Pomegranate"=>2, "Raspberry"=>9, "Miracle fruit"=>5}
Use each_with_object:
product_name.zip(product_quantity)
.each_with_object({}) {|(k, v), h| h[k] ? h[k] += v : h[k] = v }
#=> {"Pomegranate"=>2, "Raspberry"=>9, "Miracle fruit"=>5}
Or just use hash with default value:
product_name.zip(product_quantity)
.each_with_object(Hash.new(0)) {|(k, v), h| h[k] += v }
#=> {"Pomegranate"=>2, "Raspberry"=>9, "Miracle fruit"=>5}
Hash.new(0)
I would start with something like this:
product_name.zip(product_quantity)
.group_by(&:first)
.map { |k, v| [k, v.map(&:last).inject(:+)] }
.to_h
#=> { "Pomegranate" => 2, "Raspberry" => 9, "Miracle fruit" => 5}
I suggest to lookup each method in the Ruby's docs for Array and Hash and to check in the console what each the intermediate step returns.
This is but a slight variation of @llya's solution #2.
product_name.each_index.with_object(Hash.new(0)) { |i,h|
h[product_name[i]] += h[product_quantity[i]] } .
Couldn't we just do:
product_name.zip(product_quantity).to_h
Seems to return the correct result for me?
