Instead of mapply, use lapply (it is more appropriate in this case anyway as you have only one list that you need to iterate over):
lapply(df.list, function(x) coxph(form, x)) -Christos > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Erik Iverson > Sent: Thursday, November 08, 2007 4:43 PM > To: '[EMAIL PROTECTED]' > Subject: [R] mapply, coxph, and model formula > > Hello - > > I am wanting to create some Cox PH models with coxph (in package > survival) using different datasets. > > The code below illustrates my current approach and problem > with completing this. > > ### BEGIN R SAMPLE CODE ############################## > library(survival) > > #Define a function to make test data > makeTestDF <- function(n) { > times <- sample(1:200, n, replace = TRUE) > event <- rbinom(n, 1, prob = .1) > trt <- rep(c("A","B"), each = n/2) > testdf <- data.frame(times,event,trt) } > > #Create two sets of test data of different sizes > testdf1 <- makeTestDF(100) > testdf2 <- makeTestDF(200) > > #Define a formula and call coxph > form <- Surv(times, event) ~ trt > coxph(form, testdf1) #Works > coxph(form, testdf2) #Works > > #Create a list of the two data.frames > df.list <- list(testdf1, testdf2) > > #Try to use mapply > mapply(coxph, form, df.list) > > ### END R SAMPLE CODE ############################### > > The mapply call generates the following message: > > Error in terms.default(formula, special, data = data) : > no terms component > > It appears from debugging that the formula argument passed > into coxph is simply `~` in this case, with class "name" > instead of "formula". > > Any ideas on how I can get this to work using this approach? > > Best, > Erik Iverson > [EMAIL PROTECTED] > > > sessionInfo() > R version 2.5.1 (2007-06-27) > i686-pc-linux-gnu > > locale: > LC_CTYPE=en_US.UTF-8;LC_NUMERIC=C;LC_TIME=en_US.UTF-8;LC_COLLA > TE=en_US.UTF-8;LC_MONETARY=en_US.UTF-8;LC_MESSAGES=en_US.UTF-8 > ;LC_PAPER=en_US.UTF-8;LC_NAME=C;LC_ADDRESS=C;LC_TELEPHONE=C;LC > _MEASUREMENT=en_US.UTF-8;LC_IDENTIFICATION=C > > attached base packages: > [1] "grid" "grDevices" "datasets" "tcltk" "splines" > "graphics" > [7] "utils" "stats" "methods" "base" > > other attached packages: > debug mvbutils SPLOTS_1.2-6 reshape SPLOTS_1.3-22 > "1.1.0" "1.1.1" "1.2-6" "0.8.0" "1.3-22" > Hmisc chron survival > "3.4-2" "2.3-13" "2.32" > > ______________________________________________ > [email protected] mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > > ______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
