search for: convhulln

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 expand...

Hi All, convhulln {geometry} computes the convex hull of a set of points in n- dimensions via .call, returning the hull itself, and also "unavoidably generates a diagnostic report on an Rterm console." See the example below. I need to access the results of the diagnostic report (specifically the c...

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 <- matrix(c(1,0,0,1),ncol=2) > Y <- rmvnorm(n=100,mean=Mean,sigma=Sigma) > hull <- convhulln(Y) > hull [,1] [,2] [1,] 16 26 [2,] 16...

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 for finding convex hull in multi-dimensional case, that is more than 3- dimension. Thank you in advance.

...anks in advance Miltinho Astronauta Brazil ----- require(geometry) library(rgl) x<-rnorm(100) k<-runif(100)*20+5 y<-rnorm(100) z<-sin(x)+cos(y)^2 my.data.3d<-data.frame(cbind(x,y,z)) my.data.3d = sqrt(3) * my.data.3d / drop(sqrt((my.data.3d^2) %*% rep(1,3))) data.ts.surf = t( convhulln(my.data.3d,"QJ") ) # see the qhull documentations for the options ## Not run: rgl.triangles(my.data.3d[data.ts.surf,1],my.data.3d[data.ts.surf,2],my.data.3d[data.ts.surf,3],col="blue",alpha=.2) for(i in 1:(8*360)) rgl.viewpoint(i/8) [[alternative HTML version deleted]]

Dear R, I have a covariates matrix with 10 observations, e.g. > X <- matrix(rnorm(50), 10, 5) > X [,1] [,2] [,3] [,4] [,5] [1,] 0.24857135 0.30880745 -1.44118657 1.10229027 1.0526010 [2,] 1.24316806 0.36275370 -0.40096866 -0.24387888 -1.5324384 [3,] -0.33504014 0.42996246 0.03902479 -0.84778875 -2.4754644 [4,] 0.06710229 1.01950917

You may use the "geometry" package and the "convhulln" function. This will allow you to compute the convex hull volume of a set of points in a n-dimensional space. -- Guilhaumon Fran?ois Laboratoire "Ecosyst?mes Lagunaires" UMR 5119 cc 93 Bat 24 Universit? Montpellier II 34 095 Montpellier France http://www.ecolag.univ-montp2.fr htt...

...quot;, w.abun = T, CWM.type = "all" ) FRic: Dimensionality reduction was required. The last PCoA axis (out of 6 in total) was removed. FRic: Quality of the reduced-space representation = 0.9402678 QH6114 qhull precision error: initial simplex is not convex. Distance=-2.7e-15 Error in convhulln(tr.FRic, "FA") : Received error code 2 from qhull. Best, Elisae [[alternative HTML version deleted]]

Dear friends, Do you know how to calculate the CONCAVE hull of a set of points (2- dimensional or n-dimensional)? is that possible in R? (With a "smoothing" parameter of course). Best, -- Corrado Topi Global Climate Change & Biodiversity Indicators Area 18,Department of Biology University of York, York, YO10 5YW, UK Phone: + 44 (0) 1904 328645, E-mail: ct529 at york.ac.uk

Hello, I have a distribution dataset for species consisting of xy coordinates at the 1km resolution, with only presence data. So a simplified example of a species distribution might be: y <- rbind(as.integer(rnorm(100,50,20)), as.integer(rnorm(200,100,30)), as.integer(rnorm(100,180,15))) x <- rbind(as.integer(rnorm(200,50,20)), as.integer(rnorm(200,100,20)), as.integer(rnorm(100,200,15)))