# spruces

##### 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.

##### Usage

`data(spruces)`

##### format

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).

##### source

Stoyan et al (1987). Original source unknown.

##### References

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.

##### Examples

```
data(spruces)
plot(spruces)
# To reproduce Goulard et al. Figure 3
plot(spruces, maxsize=5*max(spruces$marks))
plot(unmark(spruces), add=TRUE)
```

*Documentation reproduced from package spatstat, version 1.18-4, License: GPL (>= 2)*