polylist2list() extracts the vertices of the polygons from a
polylist object, seperating polygons from each other by 3 rows of NaN.
The user can then represent the coordinates of sites of a
as background map, using the option
carte included in all interactive functions of GeoXp.
It returns a matrix of numeric values with 2 columns (x and y coordinates of the vertices of the polygons) where polygons are seperated from each other by 3 rows of NaN.
Bivand R. et al. (2009), Applied Spatial Data Analysis with R, Springer.