1、?n? 1?qqpp pqpqrprqqpqqpprqrpqp )()(cPxxP?( )( )xP xP c forsomeelementc sqsrqprprpsqsrqp =KkkkppDE12log)(9142=k 1E(D)=0.940+pklog2log2pk(914514log251425E(D?)=0.971+log2(2535log235? ?35E(D?)=0.971+log2(3525log225? ?44E(D?)=0+log2(440? ?=ni 1Gain(D, A) E(D) E(Di)| Di | D |=0.2460.971(Gain(D,?)=0.94051
2、40.971514+0 +414 =KkkkppDE12log)( ()()( )P ABP A BP B=()( )P ABP A= ()P B A(|) ( )( )P B A P AP B= ()P A B () (|)0.6 0.001(|)0.006()1006 10000PPPP=? ?() (|)0.4 0.25(|)0.994()1006 10000PPPP=? ?() (|)?(|)0.833()6000 10000PPPP=? ?10000.4() (|)4000(|)0.167()6000 10000PPPP=? ?=?30.14143414P= ? ? ? ? ? ? ? ? ? ? ?=P()|?10.04741434P= ? ? ? ? ? ? ?=P()|?P? ? ? ? ? ? ? ?=0.50.141=0.0705=? ?=PP()|?P? ? ? ? ? ? ?=0.50.047=0.0235=? ?=PP()|(=)(=)PPPP=? ? ? ? ? ? ? ? ? ? ? ?(=)PPPP=? ? ? ? ? ? ? ? ? ? ? ?=()|=|?444(=)0.125888P ? ? ? ?=
