similar to: multidimensional point.in.polygon??

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 all, I have several sets of x-y-z points and I need to estimate the volume that encompass all my points. Recently I got some adivice to show the "convex hull" of my points using geometry package (see code below). But now I need to calculate the volume of my set of points. Any advice are wellcome. Thanks in advance Miltinho Astronauta Brazil ----- require(geometry) library(rgl)

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

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 computed hull volume) from within R, but I cannot see how. I've looked at

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)))

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

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

Dear all, I have a question about FD package. I?m trying to calculate functional diversity indices using insect data. My trait data includes dispersal ability (0, 0.5, 1), body size (continuous) and five feeding guilds coded as in percentages (for example; 0,0,0.5,0.5,0) since some of the species can have two different feeding guilds. However, the package only calculates when I run ?calc.Frich=

Hi there, Is there any package which can calculate the overlapping area of two polygons or output the coordinates of the overlapping of two polygons? Thanks. Haiyong

Hi there, I want to integrate a function over an irregular polygon. Is there any function which can implement this easily? Otherwise, I am thinking of divide the polygon into very small rectangles and use "adapt" to approximate it. Do you have any suggestions to get the fine division? Any advice is appreciated. Haiyong

Hello, I am trying to draw a convex-polygon (envelope) connecting the outer points (of a particular class) in a scatter plot [which I want to do to illustrate the range of a particular type of samples in an ordination plot]. Is there any function to plot this kind of polygon? Kind regards Zlatko Petrin

Dear R users, I'm trying to extract from a given matrix (GROUP) the coordinates of the vertices of the different groups (i.e. 3, 7, 1 . . .) to plot the polygons to delineate the area in which each group "wins" and colour it diferentially. I can make a simple point plot, but I would like to add polygons with full colored area. The example is with a 5x5 matrix, but I'm working

In R's maptools package, is there a built-in function to test if a given point is "inside" a given polygon on the map? The map was loaded from an ESRI Shapefile. The point's latitude and longitude are known. Thank you! Aleks -- ------------------------ Aleksandr Andreev Fulbright Fellow Graduate School of Management St Petersburg State University

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

Recently, a package for convex optimization was announced for Python, based upon the LP solver GLPK, the SDP solver in DSDP5, and the LP and QP solvers in MOSEK. I'm aware GLPK is available for R, but wondered if anyone had good packages for convex optimization along these lines for R. TIA.

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 my R buddies, I'm trying to solve a specific group of convex optimization in R. The admissible region is the inside and surface of a multi-dimensional eclipse area and the goal function is the sum of absolution values of the variables. Could any one please tell me whether there's a package in R to do this? Thank you very much, Best wishes, -- ??? Hesen Peng

I am running the following code (testing the use of the simplex function to determine if a point is in the convex hull of another set of points or not): >a <- c(0, 0) >A3 <-matrix(c(1,2,3,4,1,1), ncol = 2, byrow = T) >b3 <-c(1.5, 3.5, 1) >simplex(a = a, A3 = A3, b3 = b3) and the following error message appears: Error in simplex1(out1$a[1:(n + m1 + m2)], out1$A[, 1:(n + m1

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!