On May 26, 2015, at 8:30 AM, William Dunlap wrote: > One way to use variable names in functions like Predict() that > do not evaluate their arguments in the standard way is to use > do.call() along with as.name(). E.g., > varName<-"age" > do.call("Predict", list(fit, as.name(varName), np=4))}) > gives the same result as > Predict(fit, age, np=4) >
Here's another approach, developed after looking at the code and the help page, where I noticed that the factors argument was given an an alternate route for specifying the variables for evaluation. The requirements for the 'factors' argument are that it be provided as a named list and have either specific values or NA. var="age" vlist <- list(dum=NA) names(vlist)=var Predict(fit, factors=vlist, np=4) #----- same result ------- age yhat lower upper 1 25.04901 6.834836 4.856497 8.813174 2 41.14259 6.882369 4.919433 8.845306 3 57.23618 6.929903 4.967118 8.892688 4 73.32977 6.977437 4.999548 8.955325 Response variable (y): log odds Limits are 0.95 confidence limits -- David. > > > Bill Dunlap > TIBCO Software > wdunlap tibco.com > > On Tue, May 26, 2015 at 3:14 AM, wong jane <jane.wong...@gmail.com> wrote: > >> There are functions which use variable names as parameters in some R >> packages. However, if the variable name is stored in another variable, how >> can I pass this variable to the function. Taking the "rms" package as an >> example: >> >> library(rms) >> n <- 1000 >> age <- rnorm(n, 50, 10) >> sex <- factor(sample(c('female','male'), n,TRUE)) >> >> y <- rnorm(n, 200, 25) >> ddist <- datadist(age, sex) >> options(datadist='ddist') >> fit <- lrm(y ~ age) >> Predict(fit, age, np=4) >> options(datadist=NULL) >> >> Here "age" was a variable name passed to Predict() function, but if "age" >> was stored in variable "var", that is, var <- "age", how can I pass "var" >> to Predict() function? The purpose is that I want to change the parameter >> of Predict() in a loop. >> >> [[alternative HTML version deleted]] -- > David Winsemius Alameda, CA, USA ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.