Creates and tests for data in spatial point format.
spoints(data,npoints)spoints returns an object suitable for use as a point data
object. If npoints is given, the vector data is either truncated
or repeated until sufficient data values are generated.
The returned object is a two-column matrix, where the first column stores the
x-coordinate, and the second column stores the y-coordinate.
vector containing the data values for the points in order (x1,y1),(x2,y2),...
number of points to generate, if missing, set to length(data)/2.
Rowlingson, B. and Diggle, P. 1993 Splancs: spatial point pattern analysis code in S-Plus. Computers and Geosciences, 19, 627-655; the original sources can be accessed at: https://www.maths.lancs.ac.uk/~rowlings/Splancs/. See also Bivand, R. and Gebhardt, A. 2000 Implementing functions for spatial statistical analysis using the R language. Journal of Geographical Systems, 2, 307-317.
npts