[R] Can't there be a cd command?

[Gabor Grothendieck]

On 5/10/06, Duncan Murdoch <murdoch at stats.uwo.ca> wrote:
> On 5/10/2006 10:45 AM, Gabor Grothendieck wrote:
> > On 5/10/06, Duncan Murdoch <murdoch at stats.uwo.ca> wrote:
> >> On 5/10/2006 9:29 AM, Paul Johnson wrote:
> >> > It is a FAQ in our Linux lab.  People start emacs and fire up R via
> >> > ess, and then they have no idea 'where they are".  For computer
> >> > experts, it is not a problem, but for people who don't know much about
> >> > computers, it is a pretty big problem.  They have data in some
> >> > subdirectory, but almost invariably they don't get emacs & R started
> >> > from that same place.
> >> >
> >> > Unfortunately, for our users, it does not help to simply re-label
> >> > setwd as cd.  Both commands imply a deeper understanding of the OS
> >> > than they have.  Also, unfortunately, these are the same people who
> >> > don't understand that FAQs exist and should be consulted. These people
> >> > are so new/timid that asking in r-help would be the last thing to
> >> > cross their mind.
> >> >
> >> > I've wondered if it would not help to have the R prompt include the
> >> > directory name, as in an x terminal.
> >>
> >> I think file system directories aren't as central in R as they are in a
> >> shell, so it would just be distracting.  Most of the time I work in the
> >> R workspace, not in the file system.
> >>
> >> To me the solution is to allow interactive file selection by default,
> >> i.e. the default on read.table and similar functions should be
> >> file.choose(), rather than having no default and throwing an error.
> >> This won't help you in the short run (because file.choose() on Linux
> >> isn't all that friendly to beginners), but perhaps it would encourage
> >> someone to make it better.  file.choose() is quite nice in Windows (and
> >> I think on the Mac), so beginners there could be told
> >>
> >> mydf <- read.table()
> >>
> >> and they'd get something useful.
> >>
> >> Martin Maechler has disagreed with me about this in the past, but hasn't
> >> convinced me that he's right, he's just convinced me that doing nothing
> >> is easier than arguing about it.
> >
> > I agree with Martin regarding read.table; however, the underlying idea is
> > good and could be achieved via simple wrappers which are the same
> > as the corresponding underlying functions except for the default argument
> > to file:
> >
> >    read.table.choose <- function(file = file.choose(), ...)
> > read.table(file, ...)
> >    read.csv.choose <- function(file = file.choose(), ...) read.csv(file, ...)
> >    read.delim.choose <- function(file = file.choose(), ...)
> > read.delim(file, ...)
> >
> >   # test
> >   mydata <- read.table.choose()
> >
> > in a package available to the users or possibly even in R core.
>
> No, I don't think this is a good idea.  It would be just as easy to tell
> people to type
>
> read.table(file=file.choose())
>
> with no new package or function necessary.  I want the existing basic
> function to work when used by a beginner in a simple way.

I don't think that an idiom of multiple function calls is as simple as
issuing a single function call with no args.

One possibility is to have
a keyword "choose" on the file function in the same way that file
accepts the keyword "clipboard".  Then one could write:

  mydata <- read.table("choose")

I think the wrapper approach is probably preferable though and seems
consistent with the way R deals with this in other places such as the
ISOdate wrapper.


>
> What is it that you find objectionable about having a default for the
> file argument in read.table?  I think Martin has said that he doesn't
> want non-UI functions to be involved with UI functions, but I don't see
> that:  if your code works now, it will be completely unaffected by
> setting a default for the argument.  (Sorry if I summarized the argument
> incorrectly, Martin, I didn't look it up.)

That would be my objection too.  UI should not be tied to the non-UI core.
Its basically a loose coupling argument.