
Dear all,

I am still struggeling with the pcf (spatstat package): I try to reproduce a
plot that I did in 2005 using exactly the same point pattern (a small sample
of 18 points, extremely clustered) and the same pcf-parameters:
kernel="epanechnikov", stoyan=0.15, correction="Ripley" (code see below).
However there is a shift on the r-axis in my present plot against the one
from 2005: The form of the curve is the same, but while in 2005 I had one
prominent peak at about r=135, the same peak is now located at approx.
r=250. Also, in the earlier plot, g(r)=1 was reached at abour r=20, now at
r=55.

I checked the FAQs and Latest releases page at
http://www.spatstat.org/spatstat/, but could not find what could cause this
different behaviour of the function. Is is anyway possible that a change in
the code of the function since 2005 causes the observed differences? If not,
what else could it be?

Here my data and code:

> ab2
 planar point pattern: 18 points 
window: rectangle = [0, 1100] x [0, 824] units

> as.data.frame(ab2)
       x     y
1  182.6 767.6
2  181.4 769.4
3  183.8 769.2
4  112.4 525.0
5  113.2 534.8
6  122.2 540.6
7  128.8 544.8
8  135.8 545.6
9  135.4 539.4
10 129.2 539.8
11 125.8 529.8
12 119.6 519.4
13 129.2 521.2
14 136.2 526.0
15 140.0 531.8
16 147.8 536.6
17 366.6 559.4
18 859.2 479.4

> pcf.ppp(ab2, kernel="epanechnikov", stoyan=0.15, correction="Ripley",
r=seq(0, 400, 2.5)) ->pkfa
> plot(pkfa$r[5:400],pkfa$iso[5:400], type="l", lty=1, xlab="", ylab="");
> lines(pkftheo, col="red", lty=2, lwd=1);

Any help would be most appreciated, thanks!!!
Friderike


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