similar to: convex hulls

Dear R gurus and users, I seem to have problem finding the right tool for plotting convex hulls over 2D plots, after a cluster analysis. In fact I would like to draw a convex hull in 2D for a generic group of points. I found a "convhulln", but this doesn't seem to give me a convex hull. Here is what I do: > library(mvtnorm) > Mean <- c(2,1) > Sigma <-

Dear UseRs, I would like to know which function is the most efficient in finding convex hull of points in 3(or 2)-dimensional case? Functions for finding convex hull is the following: convex.hull (tripack), chull (grDevices), in.chull (sgeostat), convhulln (geometry), convexhull.xy (spatstat), calcConvexHull (PBSmapping). I also would like to know if there is a function that can be used

Dear list, Does anyone have a suggestion (or better still) code for sampling from the uniform distribution over the convex hull of a set of points? Many thanks and best wishes, Ranjan

Does anyone know of a R package that will determine the convex hull of a high-dimensional dataset (say 4-10 dimensions). I know chull works for 2D data. I'm neophyte to R and convex hulls so please keep it simple. Many thanks Ben -- Ben Stapley. Biomolecular Sciences, UMIST, PO Box 88, Manchester M60 1QD. Tel 0161 200 5818 Fax 0161 236 0409

Dear List Members, I'm presently carrying out morphological analysis of a data set of neuronal structures. These are essentially 3D binary trees. In due course I will be trying to use discriminant analysis or other methods to classify these neurons based on morphological variables such as total tree length, segment number etc. I would like to calculate a 3D convex hull for a set of X,Y,Z

Hi! I'm trying to use R. In S+ I use to have different projects in different directories. To make the functions and other objects from a directory available and to use that directory as default, I just do: attach(directory, pos = 1) where directory is, for example, "/home/alobo/S/bolivia1" Acutually, I have a simpe function (work) to do this: > work function(directorio) {

Dear R-users and R-developpers, I've not been able to find 3d graphics in R, like Splus spin() or brush(). Are there any that I've missed and/or is anybody working on implementing these type of functions? Thanks Dr. Agustin Lobo Instituto de Ciencias de la Tierra (CSIC) Lluis Sole Sabaris s/n 08028 Barcelona SPAIN tel 34 93409 5410 fax 34 93411 0012 alobo at ija.csic.es

Dear R makers and users. I summarize answers to my question. Thanks for your help. The conclusion seems to be that, in terms of performance with large datasets, Matlab=Octave > R > Splus5.1 > Splus5.0 but Matlab/Octave lack many of the stat functions of R/S, and, R does not have as many time-series functions as S+ (but see last message to r-announce by adrian.trapletti at

I've tried to move objects from S to R. In S+, I use data.dump() and data.restore(). I've made a file all.dum using data.dump(ls()) in S+, but the R command load("all.dum") gives an error: > load("/jaz/all.dum") Error: restore file corrupted -- no data loaded Is there any way to pass my objects from S+ to R? Thanks Agus Dr. Agustin Lobo Instituto de Ciencias de

Dear Friends, Here is an algorithm for finding concave hulls: http://get.dsi.uminho.pt/local/ Has anyone implemented such an algorithm in R? RSiteSearch('concave hull') didn't reveal one (I think). _____________________________ Professor Michael Kubovy University of Virginia Department of Psychology Postal Address: P.O.Box 400400, Charlottesville, VA 22904-4400 Express Parcels

I would like to fit a model of the type Y = Xf + e where f are cover fractions (or percent cover). Therefore, I must constrain the fit to 1. sum(f) = 1 2. 0<= f <=1 How can I introduce these 2 constraints in a ML fit? Currently, I'm using nlregb and I'm using the "upper and low" keywords to set the bounds and use the following to ensure that sum(f) = 1: let's say

I am modeling a trend surface using trmat and want to trim the resulting matrix to the area enclosed by my real data (i.e., remove all the extrapolated areas). I was using chull and in.chull to calculate the convex hull and change all the other values created by trmat to NA. However, my real data has portions that are slightly concave so chull would give me slivers that are extrapolations from

Hi everyone, Using a simulation, I have to find what are the probabilities that, in a square region, the convex hull is a triangle, using the "chull" function. However, I have a hard time with the chull function, i did not see many examples in which the chull function is used. I searched a long time on google, but I did not find nothing. So, if anyone can help, Thanks!

Hi, does anyone know if there is an implementation of qhull (http://www.qhull.org/) in R? anyone is planning on it? "Qhull computes convex hulls, Delaunay triangulations, halfspace intersections about a point, Voronoi diagrams, furthest-site Delaunay triangulations, and furthest-site Voronoi diagrams. It runs in 2-d, 3-d, 4-d, and higher dimensions. It implements the Quickhull algorithm

Hi there, I have been using the Tps function (within the Fields package) for a while now to interpolate different sedimentary units. Due to the method of formation of the units I know that at some edges the thickness of the unit decreases to zero. I was wondering if there was someway to specify that the interpolation only occurs within the convex hull of the data, outside of which the the values

Hi, I seek to identify those points in/outside a multidimensional convex hull (geometry::convhulln). Any suggestions? Background just in case I'm going down a really wrong road: Given an observed data set with one dependent/observed variable (Y) and multiple (3 to 10) independent/design variables (X1, X2, ...) I want to increase the number of points by interpolating. I'm using

Agustin Lobo asks (and I interpolate in his question) > -----Original Message----- > From: Agustin Lobo [mailto:alobo at ija.csic.es] > Sent: Monday, 23 July 2001 7:45 AM > To: r-help > Subject: [R] lapply and for > > > Given a list as such: > > > milista > $"1": > [1] 23 25 11 > > $"2": > [1] 34 2 > >

-----Forwarded Message----- > From: Ernesto Jardim <ernesto at ipimar.pt> > To: Agustin Lobo <alobo at ija.csic.es> > Subject: Re: [R-gui] NEdit Highligth patterns for R > Date: 10 Oct 2002 14:36:24 +0100 > > Hi > > You have to install the *.pats file. > > Use > > nedit -import R-5.1.pats > > then "save defaults". > > If

Thanks for your help on moving files from S+ to R and on attaching directories. If attaching directories is NOT possible in R, is there any other way to separate objects into different folders or something similar? For example, to keep user functions for multivariate analysis in a different "place" than user functions on time series, or to keep data objects of project_1 in a different

Thanks for your help on moving files from S+ to R and on attaching directories. If attaching directories is NOT possible in R, is there any other way to separate objects into different folders or something similar? For example, to keep user functions for multivariate analysis in a different "place" than user functions on time series, or to keep data objects of project_1 in a different