Spruces Point Pattern
The data give the locations of Norwegian spruce trees in a natural forest stand in Saxonia, Germany. Each tree is marked with its diameter at breast height.
data(spruces)
An object of class "ppp"
representing the point pattern of tree locations
in a 56 x 38 metre sampling region. Each tree is marked
with its diameter at breast height. All values are given in metres.
See ppp.object for details of the format of a
point pattern object. The marks are numeric.
These data have been analysed by Fiksel (1984, 1988), Stoyan et al (1987), Penttinen et al (1992) and Goulard et al (1996).
Stoyan et al (1987). Original source unknown.
Fiksel, T. (1984) Estimation of parameterized pair potentials of marked and nonmarked Gibbsian point processes. Elektron. Informationsverarb. u. Kybernet. 20, 270–278.
Fiksel, T. (1988) Estimation of interaction potentials of Gibbsian point processes. Statistics 19, 77-86
Goulard, M., S\"arkk\"a, A. and Grabarnik, P. (1996) Parameter estimation for marked Gibbs point processes through the maximum pseudolikelihood method. Scandinavian Journal of Statistics 23, 365–379.
Penttinen, A., Stoyan, D. and Henttonen, H. (1992) Marked point processes in forest statistics. Forest Science 38, 806–824.
Stoyan, D., Kendall, W.S. and Mecke, J. (1987) Stochastic Geometry and its Applications. Wiley.
if(require(spatstat.geom)) {
plot(spruces)
# To reproduce Goulard et al. Figure 3
# (Goulard et al: "influence zone radius equals 5 * stem diameter")
# (help(plot.ppp) says: "size of symbol = diameter")
plot(spruces, maxsize=10*max(spruces$marks))
plot(unmark(spruces), add=TRUE)
}Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.