either a matrix or data.frame with two columns,
a list with components x and y, or an object of any
class that can be used for maps and provides its own plot method
(e.g., "SpatialPol
add
a logical indicating whether map should be
added to an already existing plot (the default is FALSE).
...
further arguments and graphical parameters to be passed
to plot and/or lines.
References
M. Templ, A. Alfons, P. Filzmoser (2012)
Exploring incomplete data using visualization tools.
Journal of Advances in Data Analysis and Classification, Online first. DOI: 10.1007/s11634-011-0102-y.