similar to: Problems creating a random sample

Hi, I have the following piece of code that is part of a larger function. This piece is the most time consuming part of the function, and I would like to make this a bit more efficient. Could anyone suggest a way to do this faster? In particular, I would like to replace the nested "for" loop with a faster construct. I tried things like "kronecker" and "outer"

I am moving this to r-devel. The problem and solution below posted on r-help could have been a bit slicker if %*% worked with multidimensional arrays multiplying them so that if the first arg is a multidimensional array it is mulitplied along the last dimension (and first dimension for the second arg). Then one could have written: Tbar <- tarray %*% t(wt) / rep(wti, each = 9) which is a bit

Hello, I would like to simulate randomly from a multivariate normal distribution using a correlation matrix, rho. I do not have sigma. I have searched the help archive and the R documentation as well as doing a standard google search. What I have seen is that one can either use rmvnorm in the package: mvtnorm or mvrnorm in the package: MASS. I believe I read somewhere that the latter was

Dear all, The MASS library provides a mvrnorm function to generate random numbers from a multivariate normal distribution, similar to S-Plus's rmvnorm, but is there an R-equivalent to pmvnorm, which generates probabilities from a multivariate normal? With thanks, John Field -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read

Dear?All, ? a few weeks ago I have posted a question on the R help listserv that?some of you have responded to with a great solution, would like to thank you for that? again.?I thought I would reach out to you with the issue I am trying to solve now. I have posted the question a few days ago, but probably it was not?clear enough, so I thought i try it again.?At times I have a multivariate example

Dear R-devel list members, Ben Fairbank draw it to my attention that factanal() (in the stats package) doesn't report factor correlations for oblique rotations. Looking at the source, I see that factanal also doesn't save the factor-transformation (rotation) matrix from which these correlations can be computed. I've modified the source, attached below, so that the transformation

Hi, Try: dat1<- t(dat[,-1]) ?colnames(dat1) <- dat[,1] covmat <- cov(dat1) A.K. I'm running into this error and I'm not sure how fix it Error: is.numeric(x) || is.logical(x) is not TRUE This is my data frame geneExpression_Lab10.txt This is the homework instructions in case you want to see Lab10.pdf This is my code dat <-read.delim("~/Dropbox/Homework/R

R version: 1.7.1 OS: Red Hat Linux 7.2 When "covmat" is supplied in princomp(), the output value "center" is all NA's, even though the input matrix was indeed centered. I haven't read anything about this in the help file for princomp(). See code below for an example: pc2$center is all NA's. Jerome Asselin x <- rnorm(6) y <- rnorm(6) X <- cbind(x,y)

On 4 Jan 2003 at 12:51, Wolfgang Lindner wrote: > Please excuse me, if the following questions are *too* off-topic, but I found it > interesting. In inspecting your code I came across an R feature, I could not > find in the online manuals: > > Q1. Looking at the left-handside in your function def: > > "cov.cor" <- function ( covmat ) { >

Dear List, First off, my deepest gratitude to the Sweave developers: this tool has improved my quality greatly. A question in my work I use \Sexpr{} statements scalar values and the xtable package for all manner of tables. What I'd like to do is to use a vector inline, rather than a whole separate table. Something like: %%%%%%%%%%%%%%%% begin code % Latex junk % Sweave block:

Dear R-helpers, I´m in the context of writing a general function for error propagation in R. There are somehow a few questions I would like to ask (discuss), as my statistical knowledge is somewhat restricted. Below is the function I wrote, the questions are marked. Many thanks in advance. propagate <- function(expr, varList, type = c("stat", "raw"), cov = TRUE) {

Dear list, I am trying to use the 'mvrnorm' function from the MASS package for simulating multivariate Gaussian data with given covariance matrix. The diagonal elements of my covariance matrix should be the same, i.e., all variables have the same marginal variance. Also all correlations between all pair of variables should be identical, but could be any value in [-1,1]. The problem I am

--=-hiYzUeWcRJ/+kx41aPIZ Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit Hi, on March 10 I filed a wishlist bug report asking for the inclusion of some changes to factanal() and the associated print method. The changes were originally proposed by John Fox in 2005; they make print.factanal() display factor correlations if factanal() is called with rotation =

Hi, My R version is 2.4.1 and I installed the the packages MASS and run command library("MASS"), however when I type ?rmvnorm, no help topic found, it worked before. I tried to ype ?rinvgamma from "MCMCpack" which works great. Anybody have idea? I also reinstalled MASS package, but when I try to type rmvnorm(), no functions found. Pat

Hi, I had a look at the MASS4 scripts in the MASS package, in Ch 11.3 Factor Analysis, there is a section of codes like: data(ability.cov) ability.FA <- factanal(covmat = ability.cov, factors = 1) ability.FA (ability.FA <- update(ability.FA, factors = 2)) #summary(ability.FA) round(loadings(ability.FA) %*% t(loadings(ability.FA)) + diag(ability.FA$uniq), 3)

Dear list, here is something I do not understand about cov.rob. > dat <- rmvnorm(200,rep(0,10),diag(10)) > cov.rob(dat,method="mcd") > cov.rob(dat,method="mcd",quantile.used= floor(3*211/4)) # All fine; default for quantile.used is floor(211/2) > dat <- rmvnorm(20,rep(0,10),diag(10)) > cov.rob(dat,method="mcd") # quantile.used is floor(31/2).

Dear All I want to generate multivariate normal data in R for a given covariance matrix, i.e. my generated data must have the given covariance matrix. I know the rmvnorm command is to be used but may be I am failing to properly assign the covariance matrix. Any help will be greatly appreciated thanks. M. R. Ahmad

Hi, I have a set of covariance matrices but not the original data. I want to carry out some exploratory factor analysis. So, I am trying to construct a covariance matrix list as the input for factanal. I can construct a list which includes the cov, the centers, and the n.obs. But it doesn't work. I get an error that says "Error in sqrt(diag(cv)) : Non-numeric argument to mathematical

Hi! After unziping the CRAN file e1071.zip on my Win95 library directory, I start R and type >library(e1071) After that, help commands of the e1071 functions work (i.e., help(read.pnm), BUT some functions themselves are not available: > read.pnm Error: Object "read.pnm" not found I've looked at the file library/R/e1071 with an ascii editor and it seems like the functions

Hello, 1) I am interested in performing a limited-dependent variable linear regression. By this I mean a classical linear regression, but for the case where the values of the dependent variable cannot vary from -infinity to +infinity, but are truncated and so are between two finite limits L1 and L2. Does R1.7 have this capability? If so what is (are) the relevant command(s)? 2) I am also