Import packages
library(ggplot2)
Scatter plot of miles per gallon, mpg, against weight, wt, by number of forward gears, gear, from mtcars dataset
mtcars$gear <- as.character(mtcars$gear) # convert gear to character
ggplot(mtcars, aes(x = wt, y = mpg, color = gear)) + geom_point(size = 0.7) + geom_smooth(method = lm, se = TRUE) + ggtitle("Weight vs. miles per gallon by gear") + theme_bw() + theme(text = element_text(size = 18)) # fitting a linear model with standard error (shown by shaded area)
