if(m_Distributions == null) m_Distributions = new FastVector(); m_Distributions.addElement(classCounts);
  public void addAndUpdate(Rule lastRule){    if(m_Ruleset == null)      m_Ruleset = new FastVector();    m_Ruleset.addElement(lastRule);    Instances data = (m_Filtered == null) ?      m_Data : ((Instances[])m_Filtered.lastElement())[1];    double[] stats = new double[6];    Instances[] filtered =       computeSimpleStats(m_Ruleset.size()-1, data, stats);    if(m_Filtered == null)      m_Filtered = new FastVector();	    m_Filtered.addElement(filtered);    if(m_SimpleStats == null)      m_SimpleStats = new FastVector();	    m_SimpleStats.addElement(stats);  }