Pacific Centric Low resolution World Map
This world database comes from a thinned cleaned-up version of the CIA World Data Bank II data and contains approximately 30,000 points representing the world coastlines and national boundaries. The full database of nearly 2 million points is found in the mapdata package. This map is based on latitudes [0, 360), which then has the Pacific Ocean in the centre of the map.
The same effect can in fact be obtained by using a projection:
By changing the third component of 'orientation', the longitude shift can also be set to any other value besides 180 or 0 (but then fill=TRUE will usually give artefacts at the borders). You may even need to set 'resolution=0' if the wrapping algorithm fails because of the thinning.
This method is in fact to be preferred, as it will also render correctly with fill=TRUE. Currently, the wrapping code does not work well with world2.
The data file is merely a character string which
specifies the name of an environment variable which contains the
base location of the binary files used by the map drawing functions.
This environment variable (
R_MAP_DATA_DIR_WORLD for the datasets in the
maps package) is set at package load time if it does not
already exist. Hence setting the environment variable before loading
the package can override the default location of the binary datasets.
It is also (during a transition phase) possible to switch to the old legacy world map using the function
The Natural Earth data set is available from
The legacy CIA World Data Bank II is currently (mid-2003) available from
Richard A. Becker, and Allan R. Wilks, "Maps in S", AT&T Bell Laboratories Statistics Research Report [93.2], 1993.
Richard A. Becker, and Allan R. Wilks, "Constructing a Geographical Database", AT&T Bell Laboratories Statistics Research Report [95.2], 1995.
map('world2', xlim = c(100, 300)) map.axes()