CODEWITHSUNDEEP
rggplot2regression
luciano
luciano

Reputation: 13792

plot linear regressions lines without interaction in ggplot2

This code plots regression lines with interactions in ggplot2:

library(ggplot2)
ggplot(mtcars, aes(hp, mpg, group = cyl)) + geom_point() + stat_smooth(method = "lm")

enter image description here

Can lines without interactions be plotted with stat_smooth?

Upvotes: 6

Views: 2793

Answers (1)

Didzis Elferts
Didzis Elferts

Reputation: 98439

Workaround would be to make model outside the ggplot(). Then make predicition for this model and add result to the original data frame. This will add columns fit, lwr and upr.

mod<-lm(mpg~factor(cyl)+hp,data=mtcars)
mtcars<-cbind(mtcars,predict(mod,interval="confidence"))

Now you can use geom_line() with fit values as y to add three regression lines and geom_ribbon() with lwr and upr to add confidence interval.

ggplot(mtcars, aes(hp, mpg, group = cyl)) + geom_point() +
      geom_line(aes(y=fit))+geom_ribbon(aes(ymin=lwr,ymax=upr),alpha=0.4)

enter image description here

Upvotes: 7

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