Cosine Similarity

cosine_similarity.rb

class Cosine
  def initialize(vecA, vecB)
    @vecA = vecA
    @vecB = vecB
  end

  def calculate_similarity
    return nil unless @vecA.is_a?(Array) && @vecB.is_a?(Array) && @vecA.size == @vecB.size
    
    dot_product = @vecA.each_with_object(0).with_index { |(v1i, sum), i| sum += v1i * @vecB[i] }
    a = @vecA.zip(@vecA).map { |v1i, v2i| v1i**2 }.sum
    b = @vecB.zip(@vecB).map { |v1i, v2i| v1i**2 }.sum
    
    square_root = Math.sqrt(a) * Math.sqrt(b)
    square_root == 0 ? 0 : dot_product / square_root
  end
end