[R-sig-Geo] Unexpected output from distfun

[Rolf Turner]

Okay --- I think I've tracked it down.  The problem is (I believe) with 
the value
of "huge" in the nncross() function --- which just isn't huge enough.  
It was taken
to be the diameter of X$window, which could in fact be quite small 
relative to
the distances between the points of X and the points of Y (and will in 
fact be
*zero* when applying the function returned by distfun() if the argument to
distfun() has only one point).

I've amended nncross() to take "huge" to be the diameter of

     union.owin(X$window,Y$window)

This seems to work ... although there may be a better strategy.  (Over 
to you,
Adrian).

I have attached my amended version of nncross, which you can source into
you can use until a release of "spatstat" containing this, or a more 
appropriate fix
comes out.

Note that you need to do

     assignInNamespace("nncross",nncross,"spatstat")

after sourcing in nncross.R, otherwise distfun() will use the "old" 
version of nncross
rather than the amended one.  And you have to (psigh!) do the 
assignInNamespace()
thing each time you start a new R session, in order to get the right 
nncross() function
being called.

     cheers,

         Rolf Turner

On 15/01/12 11:55, ONKELINX, Thierry wrote:
> Dear all,
>
> I'm not getting the output I'm expecting when using distfun() from the 
> spatstat package. Any idea what is going wrong?
>
> Best regards,
>
> Thierry
>
> library(spatstat)
> w <- owin(xrange = c(-10, 10), yrange = c(-10, 10))
> P <- ppp(x = 0, y = 0, window = w)
> P1 <- ppp(x = 1, y = 0, window = w)
> P2 <- ppp(x = 1:2, y = c(1, 1), window = w)
> P3 <- ppp(x = 2:1, y = c(2, 2), window = w)
> f <- distfun(P)
> f2 <- distfun(P2)
> fo <- list(f(P1), f(P2), f(P3))
> fo2 <- list(f2(P), f2(P1), f2(P3))
>
> > fo
> [[1]]
> [1] 0
>
> [[2]]
> [1] 1 1
>
> [[3]]
> [1] 1 1
>
> > fo2
> [[1]]
> [1] 0
>
> [[2]]
> [1] 0
>
> [[3]]
> [1] 1 1
>
> > sessionInfo()
> R version 2.14.1 (2011-12-22)
> Platform: x86_64-pc-linux-gnu (64-bit)
>
> locale:
>  [1] LC_CTYPE=nl_BE.UTF-8       LC_NUMERIC=C
>  [3] LC_TIME=nl_BE.UTF-8        LC_COLLATE=nl_BE.UTF-8
>  [5] LC_MONETARY=nl_BE.UTF-8    LC_MESSAGES=nl_NL.UTF-8
>  [7] LC_PAPER=C                 LC_NAME=C
>  [9] LC_ADDRESS=C               LC_TELEPHONE=C
> [11] LC_MEASUREMENT=nl_BE.UTF-8 LC_IDENTIFICATION=C
>
> attached base packages:
> [1] stats     graphics  grDevices utils     datasets  methods   base
>
> other attached packages:
> [1] spatstat_1.25-1 deldir_0.0-16   mgcv_1.7-12
>
> loaded via a namespace (and not attached):
> [1] grid_2.14.1    lattice_0.20-3 Matrix_1.0-3   nlme_3.1-102
>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://stat.ethz.ch/pipermail/r-sig-geo/attachments/20120115/5f91f1eb/attachment.html>
-------------- next part --------------
An embedded and charset-unspecified text was scrubbed...
Name: nncross.R
URL: <https://stat.ethz.ch/pipermail/r-sig-geo/attachments/20120115/5f91f1eb/attachment.pl>