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Fix infinite recursion.

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Rusty Klophaus
2013-01-15 14:45:18 -05:00
parent a714dcecf7
commit dafd3ea7f8
2 changed files with 21 additions and 1 deletions
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7
lib/decisiontree/id3_tree.rb
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@@ -69,9 +69,14 @@ module DecisionTree
# return classification if all examples have the same classification
return data.first.last if data.classification.uniq.size == 1
# Choose best attribute (1. enumerate all attributes / 2. Pick best attribute)
# Choose best attribute:
# 1. enumerate all attributes
# 2. Pick best attribute
# 3. If attributes all score the same, then pick a random one to avoid infinite recursion.
performance = attributes.collect { |attribute| fitness_for(attribute).call(data, attributes, attribute) }
max = performance.max { |a,b| a[0] <=> b[0] }
min = performance.min { |a,b| a[0] <=> b[0] }
max = performance.shuffle.first if max == min
best = Node.new(attributes[performance.index(max)], max[1], max[0])
best.threshold = nil if @type == :discrete
@used.has_key?(best.attribute) ? @used[best.attribute] += [best.threshold] : @used[best.attribute] = [best.threshold]