Class: HybridForest::Trees::Entropy

Inherits:
Object
  • Object
show all
Includes:
Impurity
Defined in:
lib/hybridforest/trees/impurity_metrics/entropy.rb

Instance Method Summary collapse

Methods included from Impurity

#information_gain, #weighted_impurity

Instance Method Details

#compute(instances) ⇒ Object 



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# File 'lib/hybridforest/trees/impurity_metrics/entropy.rb', line 10

def compute(instances)
  instance_count = instances.count
  label_counts = instances.count_labels
  label_counts.values.sum do |label_count|
    label_probability = label_count.to_f / instance_count
    label_surprise = Math.log2(1 / label_probability)
    label_probability * label_surprise
  end
end