On Thu, Apr 7, 2011 at 7:45 PM, Franklin Tamborello II <[email protected]> wrote: > I know my subject line seems odd, but I want to replace an expression—such as > a variable—with its value. For example, I want to paste() some strings > together, assign the result to a variable s, then use the value of s as a > variable to hold another value. Something like this: > > import_subjects <- function (start, iterations) { > for (i in 1:iterations) { # iterate from start to end > s <- paste("s", i, sep="") # make the data.frame's name > fn <- paste(i, ".txt", sep="") # make the filename > s <- read.delim(fn, header = FALSE) # now put it all together > # …except that I don't want to reassign s, I want to evaluate it and make its > value a variable with its own value. > } > } > > If this were Lisp I'd use backquotes (or "backticks", as some say) and > commas—examples of read macros—to do this, but I can't find anything > analogous for R. How might I accomplish this in R? >
Here are a few possibilities: # 1 - assign assign(s, read.delim(fn, header = FALSE) # 2 - .GlobalEnv .GlobalEnv[[s]] <- read.delim(fn, header = FALSE) # 3 - gsubfn's fn$ supports backticks # Here we need gsubfn::fn to disambiguate the two fn's library(gsubfn) eval(gsubfn::fn$parse(text = " `s` <- read.delim(fn, header = FALSE) ")) -- Statistics & Software Consulting GKX Group, GKX Associates Inc. tel: 1-877-GKX-GROUP email: ggrothendieck at gmail.com ______________________________________________ [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.
