package?DecisionTree;

public?class?DTreeUtil?{
	
	public?static?double?sigma（int?x?int?total）
	{
		if?（x?==?0）
		{
			return?0;
		}
		double?x_pi?=?getPi（xtotal）;
		return?-（x_pi*logYbase2（x_pi））;
	}

	
	public?static?double?logYbase2（double?y）
	{
		return?Math.log（y）?/?Math.log（2）;
	}
	
	
	public?static?double?getPi（int?x?int?total）
	{
		return?x?*?Double.parseDouble（“1.0“）?/?total;
	}
}

?屬性????????????大小?????日期????時(shí)間???名稱
-----------?---------??----------?-----??----
?????目錄???????????0??2012-09-09?18:08??ID3\
?????文件?????????232??2012-09-09?18:08??ID3\.classpath
?????文件?????????379??2012-09-09?18:08??ID3\.project
?????目錄???????????0??2012-09-10?10:32??ID3\bin\
?????目錄???????????0??2012-09-10?10:32??ID3\bin\DecisionTree\
?????文件?????????750??2012-09-10?11:16??ID3\bin\DecisionTree\DTreeUtil.class
?????文件????????7568??2012-09-10?15:30??ID3\bin\DecisionTree\ID3.class
?????文件?????????698??2012-09-09?19:16??ID3\bin\DecisionTree\SequenceComparator.class
?????文件?????????471??2012-09-09?18:22??ID3\bin\DecisionTree\TreeNode.class
?????目錄???????????0??2012-09-10?10:32??ID3\src\
?????目錄???????????0??2012-09-10?10:32??ID3\src\DecisionTree\
?????文件?????????422??2012-09-10?11:16??ID3\src\DecisionTree\DTreeUtil.java
?????文件????????8794??2012-09-10?15:30??ID3\src\DecisionTree\ID3.java
?????文件?????????280??2012-09-09?19:16??ID3\src\DecisionTree\SequenceComparator.java
?????文件?????????278??2012-09-09?18:22??ID3\src\DecisionTree\TreeNode.java