A multiclass decision tree example

multiclass_decision_tree.R

library(rpart)
library(tidyverse)
library(ggdendro)

ggplot(data = iris, 
       aes(Sepal.Length, Petal.Length, color = Species))+
  geom_point()

dt <- rpart(Species ~ Sepal.Length + Petal.Length, 
            data = iris, 
            method = 'class')

printcp(dt)
plotcp(dt) #cross validation error


ddata <- dendro_data(dt)
ggplot() + 
  geom_segment(data = ddata$segments, 
               aes(x = x, y = y, xend = xend, yend = yend)) + 
  geom_text(data = ddata$labels, 
            aes(x = x, y = y, label = label), size = 3, vjust = 0) +
  geom_text(data = ddata$leaf_labels, 
            aes(x = x, y = y, label = label), size = 3, vjust = 1) +
  theme_void()