Introduction to ggplot2 - R Graphics - page 470

base graphics, we don't have to change the data; we just change the commands for making the
graph:
ggplot(simpledat_long, aes(x = Bval, y = value, fill = Aval)) +
geom_bar(stat = "identity" , position = "dodge" )
Figure A-5. Bar graph of the same data, but with x and fill mappings switched
NOTE
You may have noticed that with ggplot2, components of the plot are combined with the + operator. You
can gradually build up a ggplot object by adding components to it, then, when you're all done, you can
tell it to print.
To change it to a line graph ( Figure A-6 ), we change geom_bar() to geom_line() . We'll also
map Bval to the linecolor, with colour , instead of the illcolour (note the British spelling—the
author of ggplot2 is a Kiwi). Again, don't worry about the other details yet:
ggplot(simpledat_long, aes(x = Aval, y = value, colour = Bval, group = Bval)) +
geom_line()