Quickly Exploring Data - R Graphics - page 11

lines(pressure$temperature, pressure$pressure / 2 , col = "red" )
points(pressure$temperature, pressure$pressure / 2 , col = "red" )
With ggplot2, you can get a similar result using qplot() with geom="line" ( Figure 2-4 ):
library(ggplot2)
qplot(pressure$temperature, pressure$pressure, geom = "line" )
Figure 2-4. Left: line graph with qplot() from ggplot2; right: with points added
If the two vectors are already in the same data frame, you can use the following syntax:
qplot(temperature, pressure, data = pressure, geom = "line" )
# This is equivalent to:
ggplot(pressure, aes(x = temperature, y = pressure)) + geom_line()
# Lines and points together
qplot(temperature, pressure, data = pressure, geom = c( "line" , "point" ))
# Equivalent to:
ggplot(pressure, aes(x = temperature, y = pressure)) + geom_line() + geom_point()
See Also
See Chapter 4 for more in-depth information about creating line graphs.