search for: petertait

Hi, I am reading a "|" delimited text file into R using read.table(). I am using colClasses= to specify some variables as factors. Some of these variables include missing values coded as "NA". Unfortunately the R code I am using (pasted bellow) includes "NA" as one of the factor levels. Is it possible to remove the "NA" level from a factor with in

Hi All, I am in the middle of doing an analysis of a Case-Cohort design. I had three questions about the analysis: a) Does any one know of some public code for developing the patient risk sets (indexed by failure time) or is there a better way to organize the data? b) I was planning to use the Barlow weighting method. Has this or any other weighting method (Prentice, Self-Prentice) been

Hi, I am writing a basic function to extract the z scores for some linear regression coefficients: zscore<-function( y, x) { lm<-lm( y ~ x ) z <- coef(lm)/sqrt(diag(vcov(lm))) return(z) } I would like to pass a dataframe to the function as a argument so the function call changes from zscore(df$y1,df$x1) to zscore(y1,x1,data=df) but I am not sure how to reference the data

Hi, I am trying to update my version of R on Centos 4. $uname -a Linux 2.6.9-78.0.5.ELsmp #1 SMP Wed Oct 8 07:06:30 EDT 2008 x86_64 x86_64 x86_64 GNU/Linux I tried to update the current version of R (2.6.2) which was installed locally as an rpm $R --version R version 2.6.2 (2008-02-08) Copyright (C) 2008 The R Foundation for Statistical Computing ISBN 3-900051-07-0 I used yum to

Hi, I am having problems passing arguments to method="gbm" using the train() function. I would like to train gbm using the laplace distribution or the quantile distribution. here is the code I used and the error: gbm.test <- train(x.enet, y.matrix[,7], method="gbm", distribution=list(name="quantile",alpha=0.5), verbose=FALSE,

...xt/plain Hi Which package(s) is R fit frailty models to univariate survival data, i.e. simple data with one survival time per person. David [[alternative HTML version deleted]] ------------------------------ Message: 35 Date: Tue, 20 Nov 2007 14:18:45 +0000 From: "Peter Tait" <petertait at sympatico.ca> Subject: [R] randomForest() question To: r-help at stat.math.ethz.ch Message-ID: <BAY117-F251A167B3B2119A2818286CF7F0 at phx.gbl> Content-Type: text/plain; format=flowed Hi, I am trying to find some information on the strata option in randomForest(). I am hoping to make...

Hi, I have a script I can run step by step through the R interpreter and it works fine. I then run as a shell script with Rscript and it fails. The error message comes when I am creating a model matrix with model.matrix.default(). Error in `contrasts<-`(`*tmp*`, value = "contr.Treatment") : could not find function "is" Calls: model.matrix.default ->

Hi, I am using caretNWS on a RHEL x86_64 system and I am getting an error message that is nearly identical to the one occuring in http://www.r-project.org/nosvn/R.check/r-release-macosx-ix86/caretNWS-00check.txt Error in socketConnection(serverHost, port = port, open = "a+b", blocking = TRUE) : unable to open connection Calls: system.time ... .local -> tryCatch -> tryCatchList