Class: DecisionTree

Inherits:
Object
  • Object
show all
Defined in:
lib/decision_tree.rb

Constant Summary collapse

ROOT = 
'root'
LEFT = 
'left'
RIGHT = 
'right'

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(tree_xml) ⇒ DecisionTree

Returns a new instance of DecisionTree.



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# File 'lib/decision_tree.rb', line 11

def initialize(tree_xml)
  @id = tree_xml.xpath('@id')
  @root = Tree::TreeNode.new(ROOT)
  set_node(tree_xml.xpath('TreeModel/Node'), @root)
end

Instance Attribute Details

#root ⇒ Object (readonly)

Returns the value of attribute root.



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# File 'lib/decision_tree.rb', line 9

def root
  @root
end

Instance Method Details

#decide(features) ⇒ Object 



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# File 'lib/decision_tree.rb', line 29

def decide(features)
  curr = @root
  while curr.content.decision == ''
    prev = curr
    curr = curr[LEFT] if curr[LEFT] && curr[LEFT].content.true?(features)
    curr = curr[RIGHT] if curr[RIGHT] && curr[RIGHT].content.true?(features)

    return if no_true_child?(curr, prev)
  end

  curr.content.decision
end

#no_true_child?(curr, prev) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/decision_tree.rb', line 42

def no_true_child?(curr, prev)
  return false if (prev.content != curr.content)
  RandomForester.logger.error "Null tree: #{@id}, bad feature: #{curr[LEFT].content.field }"
  true
end

#set_node(tree_xml, root) ⇒ Object 



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# File 'lib/decision_tree.rb', line 17

def set_node(tree_xml, root)
  root.content = Predicate.new(tree_xml)

  return if tree_xml.xpath('*').count == 1

  root << Tree::TreeNode.new(LEFT)
  root << Tree::TreeNode.new(RIGHT)

  set_node(tree_xml.xpath('*')[1], root[LEFT]) if tree_xml.xpath('*')[1]
  set_node(tree_xml.xpath('*')[2], root[RIGHT]) if tree_xml.xpath('*')[2]
end