voronoi.mosaic chokes?

Have you tried 'debug'?

With one of the datasets that crashes your system, run the first
voronoi.mosaic, then the torus function and then

debug(voronoi.mosaic)

and run through the second call of voronoi.mosaic.  You can step though the
code and at least will you find the point where it bombs.

-----Original Message-----
From: r-help-bounces at stat.math.ethz.ch
[mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Andrew Pierce
Sent: Wednesday, May 09, 2007 12:21 AM
To: r-help at stat.math.ethz.ch
Subject: [R] voronoi.mosaic chokes?

Hi all,

I am running R 2.5.0 under Windows XP Media Center Edition.
Here's a problem that's been stumping me for a few days now,
and I can't find anything useful in the archives.  I am using
voronoi.mosaic (tripack
package) to create proximity polygons for a study of
vegetation competition and dynamics.  The points lists are
read in from a file for each plot, then 8 duplicates are
translated around the edges of the plot (Toroidal edge
correction).  This is completed using the torus(...) function
that I wrote myself.

VMuncorrected is the voronoi  mosaic that is not toroidally
edge corrected VMcorrected is the voronoi mosaic that is
toroidally edge corrected

treemap = read.table('af1.txt', sep = "\t", header = 1)
VMuncorrected = voronoi.mosaic(treemap$X, treemap$Y)

###Use the torus function to create 8 copies around the study
region  >toroid = torus(treemap$X, treemap$Y, 25, 25)

VMcorrected = voronoi.mosaic(toroid[,1], toroid[,2],

duplicate = "remove")

Here's the problem. When I read in the points for the data
file listed above ('af1.txt'), both calls to voronoi.mosaic()
work fine.  (The second one takes about 1.5 seconds because
there are 1147 points in the toroidally corrected set).

However, when I read in the points from the next file
('af2.txt'), the first call to voronoi.mosaic() works.  The
next call (to torus()) also works fine.  But the second call
to voronoi.mosaic() causes R to freeze completely requiring
Ctrl-Alt-Del.

I have 10 sets of points and this problem happens for about 5 of them.

Factors I have ruled out:
-too many points in the call (one set had 1147 and worked
fine while the next set had 801 and froze R) -duplicate
points (taken care of by voronoi.mosaic(..., duplicate =
"remove") and also independently verified by exporting the
data.  no duplicates in either the original or the toroidally
corrected set) -points too close together in space (minimum
distance between two points in 'af1.txt' is 0.1414 and works
fine.  minimum distance in the second set, 'af2.txt', is
0.2236, and this set causes R to freeze) -not enough memory
(each data set is run in a new R session-i.e. R was quit
between each attempt) -'flukiness' (the problem happens the
same way every time for the problem data sets, and the code
runs fine every time for the non-problem data sets) -file
formats (each text file has the same number of columns, all
the labels for the columns are identical, and the columns are
always in the same order) -outdated versions (I am using R
2.5.0 and updated the tripack package within the last week.
also, I update packages about once a month)

This is a very frustrating problem because I get no errors
indicating any problem with the data, and I have checked the
data over and over for any type of error and found none.  If
anyone has ANY helpful suggestions, I would love to hear
about any and all of them.

Andrew

p.s. - for those of you who are really intrigued, I can email
you the .txt files and the code for the torus() function.