Scatter Plots - R Graphics - page 114

Figure 5-17. Left: grouping into box plots; right: what happens if you don't specify groups
See Also
Instead of binning the data, it may be useful to display a 2D density estimate. To do this, see
Making a Density Plot of Two-Dimensional Data .
Adding Fitted Regression Model Lines
Problem
You want to add lines from a fitted regression model to a scatter plot.
Solution
To add a linear regression line to a scatter plot, add stat_smooth() and tell it to use meth-
od=lm . This instructs it to it the data with the lm() (linear model) function. First we'll save the
base plot object in sp , then we'll add different components to it:
library(gcookbook) # For the data set
# The base plot
sp <- ggplot(heightweight, aes(x = ageYear, y = heightIn))
sp + geom_point() + stat_smooth(method = lm)