Hello everybody, I am trying to construct Thiessenpolygons from a very large dataset (ca. 1.3 mio points) and get the following error: thiessen <- deldir(normv$X, normv$Y) [...] Fehler: lange Vektoren (Argument 7) nicht unterst?tzt in .C (~= long vectors (argument 7) not supported in .C) I am wondering if this comes from the number of points and if yes, if there is a way to split the dataset into blocks and putting the result back together afterwards? I suspect that there will be problems at the borderlines of blocks!? Thank you very much and best regards, Ludwig R version 3.0.0 (2013-04-03) Platform: x86_64-w64-mingw32/x64 (64-bit) locale: [1] LC_COLLATE=German_Germany.1252 LC_CTYPE=German_Germany.1252 LC_MONETARY=German_Germany.1252 LC_NUMERIC=C LC_TIME=German_Germany.1252 attached base packages: [1] stats graphics grDevices utils datasets methods base other attached packages: [1] sp_1.0-9 deldir_0.0-22 loaded via a namespace (and not attached): [1] grid_3.0.0 lattice_0.20-15 ----- Dipl. Geogr. Ludwig Hilger Wiss. MA Lehrstuhl f?r Physische Geographie Katholische Universit?t Eichst?tt-Ingolstadt Ostenstra?e 18 85072 Eichst?tt Tel.: 08421-93-1180 -- View this message in context: http://r-sig-geo.2731867.n2.nabble.com/Too-many-points-for-deldir-tp7583537.html Sent from the R-sig-geo mailing list archive at Nabble.com.
Too many points for deldir()
3 messages · Rolf Turner, Ludwig Hilger
2 days later
I had a similar query about a month ago, and it appears that the
limitation is intrinsic to R and there's nothing that can be done about
it through modifying deldir.
You are quite right to say that "there will be problems at the
borderlines of blocks". I would guess that doing such an amalgamation
of triangulations would be a very difficult problem. It is possible that
there is something about it in the literature; I wouldn't know.
There is another package for doing triangulation on CRAN. It's called
"tripack". This package presumably uses a different algorithm from
deldir so it is *possible* that it does not bump up against the same
limitation. You might want to give it a try. There is other software
(not written in R) out there for doing triangulation and it is possible
that one of these implementations might alleviate your problem. There
is a "sweepline algorithm" due to Steve Fortune about which I have
seen laudatory comments.
Finally, let me just say that it is mysterious to me what one could
discover from a triangulation/tessellation of 1.3 million points. It seems
to me that any potential information would be lost in a blur of noise.
Why are you doing this?
cheers,
Rolf Turner
On 11/05/13 00:05, Ludwig Hilger wrote:
Hello everybody, I am trying to construct Thiessenpolygons from a very large dataset (ca. 1.3 mio points) and get the following error: thiessen <- deldir(normv$X, normv$Y) [...] Fehler: lange Vektoren (Argument 7) nicht unterst?tzt in .C (~= long vectors (argument 7) not supported in .C) I am wondering if this comes from the number of points and if yes, if there is a way to split the dataset into blocks and putting the result back together afterwards? I suspect that there will be problems at the borderlines of blocks!?
Dear Mr. Turner, first of all: Thank you very much for you comments and hints! I will give tripack a try but I am also already working on the problem with other software. I am trying to use Thiessen polygons to assign areas of uniform change to very high-density Lidar measurement points, so the change distance measured at a point would be thought of being representative of the change within its Thiessen polygon, which will be one way of getting to Cut and Fill-Volumes. best regards and thank you again, Ludwig Hilger ----- Dipl. Geogr. Ludwig Hilger Wiss. MA Lehrstuhl f?r Physische Geographie Katholische Universit?t Eichst?tt-Ingolstadt Ostenstra?e 18 85072 Eichst?tt Tel.: 08421-93-1180 -- View this message in context: http://r-sig-geo.2731867.n2.nabble.com/Too-many-points-for-deldir-tp7583537p7583558.html Sent from the R-sig-geo mailing list archive at Nabble.com.