module Enumerable
Public Instance Methods
concitional_entropy_with(label)
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# File lib/decision-tree.rb, line 18 def concitional_entropy_with(label) dataset = Hash.new{|h,k| h[k] = Array.new } self.each_with_index{|v,i| dataset[v] << label[i] } new_entropy = 0.0 dataset.each{|k,v| new_entropy += (v.size.to_f / self.size)*v.entropy } return new_entropy end
entropy()
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# File lib/decision-tree.rb, line 5 def entropy dataset = Hash.new(0) self.each{|x| dataset[x] += 1 } entropy = 0.0 dataset.each do |k,v| p = v.to_f / self.size entropy += (-p)*Math.log2(p) end return entropy end