get filename and path of `source`d file

Question

How can a sourced or Sweaved file find out its own path?

Background:

I work a lot with .R scripts or .Rnw files. My projects are o

Answer 1

Starting from gsk3's Seb's suggestions, here's an idea:

• the combination of username (login) and IP or name of the computer could be used to select the right directory.

That leads to something like:

    setwd (switch (paste (Sys.info () [c ("user", "nodename")], collapse="."), 
           user.laptop  = "~/Messungen",
           user2.server = "~/Projekte/Projekt/",
           ))

So there is an automatic solution, that

• works with source
• works with Sweave

• even works for interactive sessions where the commands are sent line by line

• the combination of user and nodename of course needs to be specific

• the paths need to be edited by hand, though.

Improvements welcome!

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Update:

Gabor Grothendieck answered the following to a related question on r-help today:

this.dir <- dirname(parent.frame(2)$ofile)
setwd(this.dir)

which will work for source.

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Another update: I now do most of the data analysis work in RStudio. RStudio's projects basically solve the problem: RStudio changes the working directory to the project root directory every time I switch between projects.

I can therefore put the project directory as far down my directory tree as I want (and the students can also put their copy wherever they want) and sync the data files and scripts/.Rnws via version control (We use a private git server). The RStudio project files are kept out of the version control, i.e. .gitignore contains .Rproj.user.

Obviously, within the project, the directory structure needs to be synchronized.