Class: Eps::NaiveBayes

Inherits:
BaseEstimator show all
Defined in:
lib/eps/naive_bayes.rb

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from BaseEstimator

#evaluate, extract_text_features, #initialize, #predict, #summary, #to_pmml

Constructor Details

This class inherits a constructor from Eps::BaseEstimator

Instance Attribute Details

#probabilities ⇒ Object (readonly)

Returns the value of attribute probabilities.



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# File 'lib/eps/naive_bayes.rb', line 3

def probabilities
  @probabilities
end

Class Method Details

.load_pmml(data) ⇒ Object

pmml



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# File 'lib/eps/naive_bayes.rb', line 11

def self.load_pmml(data)
  super do |data|
    # TODO more validation
    node = data.css("NaiveBayesModel")

    prior = {}
    node.css("BayesOutput TargetValueCount").each do |n|
      prior[n.attribute("value").value] = n.attribute("count").value.to_f
    end

    legacy = false

    conditional = {}
    features = {}
    node.css("BayesInput").each do |n|
      prob = {}

      # numeric
      n.css("TargetValueStat").each do |n2|
        n3 = n2.css("GaussianDistribution")
        prob[n2.attribute("value").value] = {
          mean: n3.attribute("mean").value.to_f,
          stdev: Math.sqrt(n3.attribute("variance").value.to_f)
        }
      end

      # detect bad form in Eps < 0.3
      bad_format = n.css("PairCounts").map { |n2| n2.attribute("value").value } == prior.keys

      # categorical
      n.css("PairCounts").each do |n2|
        if bad_format
          n2.css("TargetValueCount").each do |n3|
            prob[n3.attribute("value").value] ||= {}
            prob[n3.attribute("value").value][n2.attribute("value").value] = BigDecimal(n3.attribute("count").value)
          end
        else
          boom = {}
          n2.css("TargetValueCount").each do |n3|
            boom[n3.attribute("value").value] = BigDecimal(n3.attribute("count").value)
          end
          prob[n2.attribute("value").value] = boom
        end
      end

      if bad_format
        legacy = true
        prob.each do |k, v|
          prior.keys.each do |k|
            v[k] ||= 0.0
          end
        end
      end

      name = n.attribute("fieldName").value
      conditional[name] = prob
      features[name] = n.css("TargetValueStat").any? ? "numeric" : "categorical"
    end

    target = node.css("BayesOutput").attribute("fieldName").value

    probabilities = {
      prior: prior,
      conditional: conditional
    }

    # get derived fields
    derived = {}
    data.css("DerivedField").each do |n|
      name = n.attribute("name").value
      field = n.css("NormDiscrete").attribute("field").value
      value = n.css("NormDiscrete").attribute("value").value
      features.delete(name)
      features[field] = "derived"
      derived[field] ||= {}
      derived[field][name] = value
    end

    Evaluators::NaiveBayes.new(probabilities: probabilities, features: features, derived: derived, legacy: legacy)
  end
end

Instance Method Details

#accuracy ⇒ Object 



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# File 'lib/eps/naive_bayes.rb', line 5

def accuracy
  Eps::Metrics.accuracy(@train_set.label, predict(@train_set))
end