Question

I’m wondering if there’s a way to do what I can do below with Python, in Ruby:

sum = reduce(lambda x, y: x + y, map(lambda x, y: x * y, weights, data)) 

I have two arrays of equal sizes with the weights and data but I can’t seem to find a function similar to map in Ruby, reduce I have working.

Answer 1

@Michiel de Mare

Your Ruby 1.9 example can be shortened a bit further:

weights.zip(data).map(:*).reduce(:+) 

Also note that in Ruby 1.8, if you require ActiveSupport (from Rails) you can use:

weights.zip(data).map(&:*).reduce(&:+)