2
从rpart
包中,可以得到以下来自printcp
功能的输出。但是如何提取根节点的错误值呢?如何从rpart printcp函数获取根节点错误值?
Classification tree:
rpart(formula = survived ~ ., data = ptitanic, control = rpart.control(cp = 1e-04))
#Variables actually used in tree construction:
#[1] age parch pclass sex sibsp
#Root node error: 500/1309 = 0.38
#n= 1309
# CP nsplit rel error xerror xstd
#1 0.4240 0 1.00 1.00 0.035
#2 0.0210 1 0.58 0.58 0.030
#3 0.0150 3 0.53 0.57 0.030
#4 0.0113 5 0.50 0.57 0.030
#5 0.0026 9 0.46 0.53 0.029
#6 0.0020 16 0.44 0.53 0.029
#7 0.0001 18 0.44 0.53 0.029