[R] precision warning in delaunayn function
Rolf Turner
rolf.turner at xtra.co.nz
Fri Jul 27 01:08:36 CEST 2012
Not answering your question but .....
coord <- as.data.frame(coord)
names(coord) <- c("x","y")
require(deldir)
tryit <- deldir(coord)
plot(tryit)
yields the attached graph. No problema.
cheers,
Rolf Turner
On 26/07/12 19:26, Jean-Luc Dupouey wrote:
> Dear R helpers,
>
> I try to use the 'delaunayn' function in the 'geometry' package for
> Delaunay triangulation in 2 dimensions.
>
> For the four following points, I get a warning message :
>
> > coord=matrix(ncol=2,byrow=TRUE,c(622633,7073452,
> + 621228,7073517,
> + 621879,7071762,
> + 621065,7073331))
> > library(geometry)
> >
> > test=delaunayn(coord,options="Qbb")
>
> qhull precision warning:
>
> The initial hull is narrow (cosine of min. angle is 0.9999999999999999).
> Is the input lower dimensional (e.g., on a plane in 3-d)? Qhull may
> produce a wide facet. Options 'QbB' (scale to unit box) or 'Qbb' (scale
> last coordinate) may remove this warning. Use 'Pp' to skip this
> warning. See 'Limitations' in qh-impre.htm.
>
> I read carefully qh-impre.htm and I still do not understand why I get
> this message. A simple call to plot(coord) shows that the points are
> not aligned, nor very close.
>
> What did I miss?
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