Graphics Reference
In-Depth Information
Figure 13-38. A map with a clean background
NOTE
There's a bug in R versions 2.15.2 and earlier, which may throw an error that looks like this:
Error in grid.Call.graphics(L_setviewport, pvp, TRUE) :
Non-finite location and/or size for viewport
This happens because some dimensions add up to having zero length, and the grid graphics engine has
trouble handling this. This bug should be fixed in R 2.16. If you're using a version of R where this
happens, you can work around it by changing the theme to use
axis.ticks.margin = unit(0.01,
"cm")
instead of
axis.ticks.margin = unit(0, "cm")
.
Discussion
In some maps, it's important to include contextual information such as the latitude and longitude.
In others, this information is unimportant and distracts from the information that's being con-
veyed. In
Figure 13-38
,
it's unlikely that viewers will care about the latitude and longitude of the
states. They can probably identify the states by shape and relative position, and even if they can't,
having the latitude and longitude isn't really helpful.
