You’ve seen how easy it is to build simple graphs in stages, starting with plot(). Now you can begin to enhance those graphs, using the many options R provides.
Changing Character Sizes: The cex Option
cex (for character expand) function allows you to expand or shrink characters within a graph, which can be very useful. You can use it as a named parameter in various graphing functions. For instance, you may wish to draw the text “abc” at some point, say (2.5,4), in your graph but with a larger font, in order to call attention to this particular text. You could do this by typing the following:
text(2.5,4,"abc",cex = 1.5)
This prints the same text as in our earlier example but with characters 1.5 times the normal size.