similar to: Test for Random Points on a Sphere

Dear All, I need to plot some points on the surface of a sphere, but I am not sure about how to proceed to achieve this in R (or if it is suitable for this at all). In any case, I am not looking for really fancy visualizations; for instance you can consider the images between formulae 5 and 6 at http://bit.ly/hOgK9h Any suggestion is appreciated. Cheers Lorenzo

Dear All, I need to do something simple: I have a set of points which are located on the surface of a sphere (let's say the centre of the sphere is in (0,0,0) and the sphere has radius R=1). How can I visualize them? I am looking for something like this http://bit.ly/PnSerU with the addition of some spots that represent some points I want to plot on the sphere surface. Any suggestion

Dear R helpers, I'm trying to write a numerical scheme for a boundary integral method to solve an electromagnetic problem. This requires the computation of the distance between points at the surface of an object (a sphere, in my example). Here is my code, > require(rgl) > r<-1 > size<-10 > theta<-seq(0,2*pi,length=size*2) > phi<-seq(0,pi,length=size) > pc

Dear All, I hope this is not too off topic. I am given a set of scatteplots (nothing too fancy; think about a normal x-y 2D plot). I do not deal with two time series (indeed I have no info about time). If I call A=(A1,A2,...) and B=(B1, B2, ...) the 2 variables (two vectors of numbers most of the case, but sometimes they can be categorical variables), I can plot one against the other and I

Not an R question directly, but has anyone got a method for placing a moderately large number of (near) equi-spaced points on a sphere? I have a nasty feeling platonic solids are needed for exact solutions and I'm thinking of samplings involving around 200 - 1000 regularly-spaced points, Thanks, Richard Rowe Richard Rowe Senior Lecturer Department of Zoology and Tropical Ecology, James

Dear All, I am not very into object-oriented programming, but I would like to learn the ropes for some R applications. Quoting from the online R language definition (paragraph 5.1) > Consider the following simple example. A point in two-dimensional > Euclidean space can be specified by its Cartesian (x-y) or polar > (r-theta) coordinates. Hence, to store information about the location

Hello veryone, I am interested in the diffusion of particles inside a sphere, and its release through a small pore on the sphere surface. Unfortunately, I have not found the way to do this in R. Could you help me? Thank very much in advance for your help

Dear R list I am using rgl.sphere to visualize scatter plot data in three dimensional space. Thanks to the rgl library, I can easily find out the data point that I am interested in. However, as I can not see the labels of each data point directly in RGL window, I usually look for the values of x, y, z axis to find out the label (or line number of the data point). Is there any way that I

Hi, I'm new to R (and math ;) Would somebody please be so kind as to direct me in plotting a 3D sphere? I tried something in the lines of: #### y <- x <- seq(-pi, pi, length=pi*10) f <- function(x,y) { z <- sqrt(pi - x^2 - y^2) #z[is.na(z)] <- 0 z } z <- outer(x, y, f) persp(x, y, z, theta = 120, phi = 30) #### I've also tried: .... make.surface.grid(...) ..

I have spatial data on a sphere (the Earth) for which I would like to run an gls model assuming that the errors are autcorrelated, i.e. including a corSpatial correlation in the model specification. In this case the distance metric should be calculated on the sphere, therefore metric = "euclidean" in (for example) corSpher would be incorrect. I would be grateful for help on how to

Hi Ralf, I tried the following > install.packages("RCurl") which went OK, but then same story when I tried to install tseries. > sessionInfo() R version 3.6.1 (2019-07-05) Platform: x86_64-pc-linux-gnu (64-bit) Running under: Debian GNU/Linux 10 (buster) Matrix products: default BLAS: /usr/lib/x86_64-linux-gnu/blas/libblas.so.3.8.0 LAPACK:

Dear All, I am far from being a guru about parallel programming. Most of the time, I rely or randomForest for data mining large datasets. I would like to give a try also to the gradient boosted methods in GBM, but I have a need for parallelization. I normally rely on gbm.fit for speed reasons, and I usually call it this way gbm_model <- gbm.fit(trainRF,prices_train, offset = NULL, misc =

Dear All, Probably a one liner, but I am banging my head against the floor. Consider the following DF <- data.frame( x=1:10, y=10:1, z=rep(5,10), a=11:20 ) mn<-names(DF) but then I cannot retrieve a column by doing e.g, DF$mn[2] I tried to play with the quotes and so on, but so far with no avail. Any suggestion is welcome. Cheers Lorenzo

There's Renka's STRIPACK, and TRIPACK, respectively, ACM TOMS Algorithms 772 and 751, and there's the R package "deldir" which does the Delaunay for a plane, but does anyone have or know of the tessellation in R for a sphere? Also, is there a standard indexing scheme for Delaunay facets, and perhaps of edges in such facets? I'd expect that to be a publication reference,

Dear All, I would like to be able to plot histograms/densities on a semi-log or log-log scale. I found several suggestions online http://tolstoy.newcastle.edu.au/R/help/05/09/12044.html https://stat.ethz.ch/pipermail/r-help/2002-June/022295.html http://www.harding.edu/fmccown/R/#histograms Now, consider the code snippet taken from http://www.harding.edu/fmccown/R/#histograms # Get a random

Dear All, I am struggling with the following problem: I am given a NxN symmetric matrix P ( P[i,i]=0, i=1...N and P[i,j]>0 for i!=j) which stands for the relative distances of N points. I would like use it to get the coordinates of the N points in a 2D plane. Of course, the solution is not unique (given one solution, I can translate or rotate all the points by the same amount and generate

Apologies for the previous mail (I sent it off too early by mistake). This is the correct example: rm(list=ls()) D_mean<-seq(-5,5,length=100) y<-exp(-D_mean^2/5) pdf("my.pdf") plot(D_mean,y,type="l",yaxt="n",lty=2,lwd=2,col="black", ylab = list(expression(paste(dN/dlogD[agg]," ["*cm^-3*"]"))), xlab = expression(paste(D[agg],"

Dear All, I am given some data to analyze. The data is in the form of a Stata database (.dta file). What is the best way to import it into an R dataframe? Is there any particular caveat I should be aware of? Many thanks Lorenzo

Dear All, Probably something very easy, but I am looking for the most efficient ways to achieve this. Consider the following snippet y<-c('a','b','c','d','e','f','g') x<-rnorm(length(y)) df<-data.frame(y,x) leading to > df$y [1] a b c d e f g Levels: a b c d e f g Now, I would like to replace levels

Dear All, I would like to use a randomForest algorithm on a dataset. The set is not particularly large/difficult to handle, but it has some missing values (both factors and numerical values). According to what I found https://stat.ethz.ch/pipermail/r-help/2005-September/078880.html https://stat.ethz.ch/pipermail/r-help/2007-January/123117.html the randomForest package has a problem with missing