Question

What is the best way to sum hash values in ruby:

@price = { :price1 => "100", :price2 => "100", :price3 => "50" }

I do something like this right now:

@pricepackage = @price[:price1] + @price[:price2] + @price[:price3] + 500

Please explain your answer, I want to learn why and not just how. =)

Answer 1

You can do:

@price.values.map(&:to_i).inject(0, &:+)

EDIT: adding explanation

So @price.values returns an array that collects all the values of the hash. That is for instance ["1", "12", "4"]. Then .map(&:to_i) applies to_i to each of the elements of this array and thus you get [1,12,4]. Lastly .inject(0,&:+) preforms inject with initial value 0 and accumulating using the function +, so it sums all the elements of the array in the last step.