Togaware DATA MINING
Desktop Survival Guide
by Graham Williams
Google

Folders and Files



> getwd()			# Identify the current default working directory
> setwd("h:/work/")		# Change the current default working directory
> file.exists("filename")	# Returns TRUE if the file exists
> unlink("filename")            # Deletes the file or directory
> fname <- file.choose()        # An interactive file chooser.
> choose.dir()			# 
> dir <- tclvalue(tkchooseDirectory()) # GUI which requires library(tcltk).

List files in a folder in the order by modification time:

> lst <- file.info(dir())
> lst[order(lst$mtime),]

MS/Windows paths use the backward slash to separate components. This is a problem since the backslash is used as a standard mechanism for introducing special characters within strings. Thus, R requires a double back slash or will seamlessly allow the use of the forward slash. A useful utility on a MS/Windows environment, where backslashes are used in paths, and R likes to have forward slashes, is the following (Duncan Golicher, 5 Jan 2006, r-help):

setwd.clip <- function()
{
  options(warn=-1)
  setwd(gsub("\\\\", "/",readLines("clipboard")))
  options(warn=0)
  getwd()
}

Then, simply select a path into your clipboard (Ctrl-C), then in R call setwd.clip:

> dir <- setwd.clip()

R packages supply files and we can access them in a installation independent way using system.file:



> system.file("csv", "audit.csv", package = "rattle")



[1] "/usr/local/lib/R/site-library/rattle/csv/audit.csv"

We can view the contents of files in R using file.show:



> file.show(system.file("csv", "audit.csv", 
                        package = "rattle"))



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