名称 是否良好 是否男
A 1 1
B 1 1
C 1 0
D 0 1
E 0 1
熵：H（D）= -[2/5log(2/5)+3/5log(3/5)]=0.971
H(D)=3/5H(D1)+2/5H(D2)=-{3/5(2/3log1/3+1/3log1/3)+2/5(1log(1)}=0.551
信息增益：IG(D,A)=0.971-0.551=0.44
信息增益率：IGr(D,A)=0.44/0.971=0.453
基尼指数 GiNi(D)=1-[(2/5)^2+(3/5)^2]
GiNi(D,A)=3/5GiNi(D1)+2/5GiNi(D2)=3/5[1-(2/3)^2+(1/3)^2]+2/5[1-1^2]=0.627