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

[Duncan Murdoch]

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.

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.)

Duncan Murdoch