similar to: two small wishes for R

without having to check the vector element by element? Thanks a lot! Jason ===== Jason G. Liao, Ph.D. Division of Biometrics University of Medicine and Dentistry of New Jersey 335 George Street, Suite 2200 New Brunswick, NJ 08903-2688 phone (732) 235-8611, fax (732) 235-9777 http://www.geocities.com/jg_liao

I have been using a laptop computer of Pentium III 1.13 Ghz. I heard that AMD's Athlon has excellent floating point capacity. So I bought a Athlon 2200+ laptop yesterday. I expected that new Athlon 2200+ will be twice as fast as the P III 1.13 GB. I ran a R simulation program and the new computer is only 30% faster, in fact slightly slower than a Celeron 1.50 GB laptop. I am very disappointed

First, I love R and am grateful to be using this free and extremely high quality software. Recently I have been comparing two algorithms and naturally I programmed in R first. It is so slow that I can almost feel its pain. So I decided to do a comparison with Java. To draw 500,0000 truncated normal, Java program takes 2 second and R takes 72 seconds. Not a computer science major, I find it hard

Hello, everyone! I guess no one is still using R on Sun Sparc these days. But our department has a (pretty new) two-CPU Sun server. We recently compiled R as a 64 bit application and expected a performance boost. But it runs 25-30% slower than the 32 bit version of R. Anyone knows why this is so? Thanks! Jason ===== Jason Liao, http://www.geocities.com/jg_liao Dept. of Biostatistics,

I am excited to learn that Prof. Tierney is bringing to us compiled R. I would like to learn when it will be available. This information will be useful in scheduling some of my projects. Thanks. Jason Jason Liao, http://www.geocities.com/jg_liao Dept. of Biostatistics, http://www2.umdnj.edu/bmtrxweb University of Medicine and Dentistry of New Jersey 683 Hoes Lane West, Piscataway‚ NJ 08854

My coauthor made a new R package GeneLogit (100% R code) which installs ok on R 2.3 on Windows. But when I type library(GeneLogit) it gave the error message Error in library(GeneLogit) : 'GeneLogit' is not a valid package -- installed < 2.0.0? It runs on R 1.9.0 just fine. It seems that others have encountered same problem but no solution is found by googling How can I fix this

Hi Jason, I suppose you installed the Matrix library, and it is working on your computer? If yes, may be det.Matrix() was removed, or renamed in the Matrix library you have (I cannot check this for the latest version, because I am away of the office until August 1st), but I will do that next week. In the meantime, you can replace 'det.Matrix' by 'det.default', and it should run.

I did some serach around. It seems that ROC curve computation is not supported on R. Anyone has some leads? Thanks. Jason ===== Jason G. Liao, Ph.D. Division of Biometrics UMDNJ School of Public Health 335 George Street, Suite 2200 New Brunswick, NJ 08903-2688 phone (732) 235-9748, fax (732) 235-9777 http://www.geocities.com/jg_liao __________________________________________________ Great

Good morning! I recently implemented a KD tree in JAVA for faster kernel density estimation (part of the code follows). It went well. To hook it with R, however, has proved more difficult. My question is: is it possible to implement the algorithm in R? My impression seems to indicate no as the code requires a complete class-object framework that R does not support. But is there an R package or

Thanks to those who responded to my inquiry about generalized linear mixed models on R and S-plus. Before I summarize the software, I note that there are several ways of doing statistical inference for generalized linear mixed models: (1)Standard maximum likelihood estimation, computationally intensive due to intractable likelihood function (2) Penalized quasi likelihood or similar

First, happy holidays, everyone! Thanks to the R team for bringing out 1.4 before the new year. I have 10000 integer triplets stored in A[1:10000, 1:3]. I would like to find the unique triplets among the 10000 ones with possible duplications. What is the easiest way for this. I know the function unique(), which apply to a vector, not the 10000*3 array in my problem. Thanks in advance. Jason

Happy new month, everyone! I am planning to write a NIH grant proposal to study ways to speed Monte Carlo based maximum likelihood algorithm for hierarchical models with a focus on generalized linear mixed models (GLM with random effects). I thought it would be nice and also increase the chance of funding if I could produce an R package in the process. I understand that Prof. Pinheiro ang Bates

Good evening! I have a multi-dimensional minimization problem whose gradient is pretty hard to code. I tried Nelder and Mead method implemented in function optim and it does not work well. I also tried the quasi Newton method in optim using difference as approximate derivative. It does not work well either. I just went through Numerical Recipes book. The book discusses another method without

One of the real advances (in my humble oppinion of course) of 2003 is the Very Fast Multivariate Kernel Density Estimation algorithm by Alex Gray which achieves several order of speed improvement by using Computational Geometry to organize the data. The algorithm is now implemented in C++ with Mathlab interface by Alexander Ihler of MIT: http://ssg.mit.edu/~ihler/code/kde.shtml I wondered if a

I have a program which needs to compute squared Euclidean distance between two vectors million of times, which the Rprof shows is the bottleneck. I wondered if there is any faster way than my own simple function distance2 = function(x1, x2) { temp = x1-x2 sum(temp*temp) } I have searched the R-help archives and can not find anything except when the arguments are matrices. Thanks for any

I recently coded a recursion algorithm in R and ir ran a few days without returning any result. So I decided to try a simple case of computing binomial coefficient using recusrive relationship choose(n,k) = choose(n-1, k)+choose(n-1,k-1) I implemented in R and Fortran 90 the same algorithm (code follows). The R code finishes 31 minutes and the Fortran 90 program finishes in 6 seconds. So the

I did several simulation sessions and the result turned out to be a surprise. After some investigation, I found that different R sessions of the program used the same seed. Simply, in R210, if I start R and type rnorm(1), I always get the same random number. This is contradictary to what is in the R document Initially, there is no seed; a new one is created from the current time when one

I have been comparing R with other languages and systems. One peculiar feature of R is there is no scalar. Instead, it is just a vector of length one. I wondered how much performance penalty this deign cause, particular in situations with many scalars in a program. Thanks. Jason Liao, http://www.geocities.com/jg_liao Associate Professor of Biostatistics Drexel University School of Public

Hello, everyone! I have spent two hours to get what I wanted in a simple situation and have not been successful. The set up is extremely simple x = c(1,2,4,8) y = c(1,2,3,4) plot(x, y) What I need, however, is for the 4 points of 1,2,4,8 to be spaced evenly, not by their numerical scale. Also, there should not be any other values such as 5,6,7 marked on the axis. So I tried the following x =

Hello, I have a data frame whose columns are factors with numeric levels and I want to convert the columns to numeric so that I can treat the data frame as a matrix. I found a way of doing this but would like to know if there is an easier way. My way is: M <- matrix(ncol=ncol(df) , nrow=nrow(df) , as.numeric(as.matrix(df))) where 'df' is the data frame. I am wondering if there is