svd_metric.rb

# encoding: utf-8
class Recommendations::Metrics::Svd < Recommendations::Metrics::MetricBase
  def initialize(klass, svd)
    @klass = klass
    @svd = svd
  end

  def compare(user_id, user_rates, sampler_id, sampler_rates)
    (@svd.user_ids.include?(sampler_id) ? @svd.rank(user_rates)[sampler_id] : nil) || 0
  end

  def cache_key(*args)
    "#{super(*args)}_#{@svd.id}"
  end
end