cut-point-regression.R

library(tidyverse)

df <- mtcars %>% 
  mutate(
    # here 20, 25 are the cut points
    region = cut(mpg, c(min(mpg), 20, 25, max(mpg)))
  )

ols <- lm(hp ~ region * mpg, df)
summary(ols)

ggplot(df, aes(mpg, hp, color = region)) +
  geom_point() +
  geom_smooth(method = "lm")