# rysunek 2.16
library("MASS")
library("class")
library("nnet")
library("tree")
attach(spam)

set.seed(123)
m <-length(spam$spam)
ucz <- sample(1:m, size = round(m/3), replace = FALSE, prob = rep(1/m, m)) 
spam.ucz <- data.frame(spam[ucz,])
spam.test <- data.frame(spam[-ucz,])

ks<-c(3:10,15, 20, 25, seq(30,100,by=10))
nks<-length(ks)
blad.ucz<-numeric(length=nks)
blad.test<-numeric(length=nks)
names(blad.ucz)<-names(blad.test)<-ks
spam.tr<-tree(spam~.,spam.ucz, mindev = 0, minsize = 2)

# rys. 2.16a
plot(spam.tr,main="Drzewo pełne")

# rys. 2.16b
spam.pr<-prune.tree(spam.tr,k=25.0)
# spam.pr<-prune.tree(spam.tr,best=10,method='misclass')
plot(spam.pr)