spatstat.data (version 3.1-2)

finpines: Pine saplings in Finland.

Description

The data record the locations of 126 pine saplings in a Finnish forest, their heights and their diameters.

The dataset finpines is a marked point pattern containing the locations of the saplings marked by their heights and their diameters.

Sapling locations are given in metres (to six significant digits); heights are in metres (rounded to the nearest 0.1 metre, except in one case to the nearest 0.05 metres); diameters are in centimetres (rounded to the nearest centimetre).

The data were recorded by Professor Seppo Kellomaki, Faculty of Forestry, University of Joensuu, Finland, and subsequently massaged by Professor Antti Penttinen, Department of Statistics, University of Jyv\"askyl\"a, Finland.

Originally the point locations were observed in polar coordinates with rather poor angular precision. Hence the coordinates are imprecise for large radius because of rounding errors: indeed the alignments can be observed by eye.

The data were manipulated by Prof Penttinen by making small angular perturbations at random. After this transformation, the original data (in a circular plot) were clipped to a square window, for convenience.

Professor Penttinen emphasises that the data were intended only for initial experimentation. They have some strange features. For example, if the height is less than 1.3 metres then the diameter can be uncertain. Also there are some very close pairs of points. Some pairs of trees (namely (58,59), (78,79), (96,97) and (102,103)) violate the requirement that the interpoint distance should be greater than half the sum of their diameters.

These data have subsequently been analysed by Van Lieshout (2004).

Usage

data(finpines)

Format

Object of class "ppp" representing the point pattern of sapling locations marked by their heights and diameters. See ppp.object for details of the format.

References

Van Lieshout, M.N.M. (2004) A J-function for marked point patterns. Research Report PNA-R0404, June 2004. Centrum voor Wiskunde en Informatica (CWI), Amsterdam, 2004.

Examples

    data(finpines)
  if(require(spatstat.geom)) {
    plot(unmark(finpines), main="Finnish pines: locations")
    plot(finpines, which.marks="height", main="heights")
    plot(finpines, which.marks="diameter", main="diameters")
    plot(finpines, which.marks="diameter", 
              main="diameters to scale", markscale=1/200)
  }