importing from rubyforge & cleanup

examples/discrete-id3.rb

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+require 'rubygems'
+require 'decisiontree'
+
+# ---Discrete-----------------------------------------------------------------------------------------
+
+# Read in the training data
+training, attributes = [], nil
+File.open('data/discrete-training.txt','r').each_line { |line| 
+  data = line.strip.split(',')
+  attributes ||= data
+  training.push(data.collect {|v| (v == 'will buy') || (v == "won't buy") ? (v == 'will buy' ? 1 : 0) : v})
+}
+
+# Remove the attribute row from the training data
+training.shift
+
+# Instantiate the tree, and train it based on the data (set default to '1')
+dec_tree = DecisionTree::ID3Tree.new(attributes, training, 1, :discrete)
+dec_tree.train
+
+#---- Test the tree....
+
+# Read in the test cases
+#    Note: omit the attribute line (first line), we know the labels from the training data
+test = []
+File.open('data/discrete-test.txt','r').each_line { |line| data = line.strip.split(',') 
+  test.push(data.collect {|v| (v == 'will buy') || (v == "won't buy") ? (v == 'will buy' ? 1 : 0) : v})
+}
+
+# Let the tree predict the output and compare it to the true specified value
+test.each { |t|   predict = dec_tree.predict(t); puts "Predict: #{predict} ... True: #{t.last}"; }
+
+# Graph the tree, save to 'discrete.png'
+dec_tree.graph("discrete")