20.18 Complexity Parameter

We can print a table of optimal prunings based on a complexity parameter using rpart::printcp(). The data is actually stored as model$cptable.

printcp(model)

## 
## Classification tree:
## rpart(formula=form, data=ds[tr, vars], model=TRUE)
## 
## Variables actually used in tree construction:
## [1] humidity_3pm rain_today  
## 
## Root node error: 31041/145946=0.21269
## 
## n= 145946 
## 
##         CP nsplit rel error  xerror      xstd
## 1 0.151413      0   1.00000 1.00000 0.0050362
## 2 0.036532      1   0.84859 0.84707 0.0047299
## 3 0.034728      2   0.81206 0.81644 0.0046620
## 4 0.010000      3   0.77733 0.77955 0.0045771

---

Your donation will support ongoing availability and give you access to the PDF version of this book. Desktop Survival Guides include Data Science, GNU/Linux, and MLHub. Books available on Amazon include Data Mining with Rattle and Essentials of Data Science. Popular open source software includes rattle, wajig, and mlhub. Hosted by Togaware, a pioneer of free and open source software since 1984. Copyright © 1995-2022 Graham.Williams@togaware.com Creative Commons Attribution-ShareAlike 4.0