[R] Genuine relative paths with R

[Duncan Murdoch]

On 10/10/2018 7:11 PM, Olivier GIVAUDAN wrote:
> It is not wrong to claim that R currently doesn't have a function 
> returning the path of the R file where this same function was invoked.

But it does.  I didn't realize that's what you were asking for.  This 
has nothing to do with your subject line.

If you source a file from somewhere, then each of the functions it 
creates is marked with its source location.  So you can put this in a file:

foo <- function () 1

filename <- normalizePath(getSrcFilename(foo, full.names=TRUE))

(You need the normalizePath() call because all that will be saved is the 
path that was used.  If it was a relative path, that's what you get 
before you normalize it.  You don't really need the foo function; you 
could put an anonymous function into the getSrcFilename call.  It's just 
usually easier to include a function that already exists.)

When you source() that file, filename will get the name of the file it 
came from.

This is a lot like __FILE__ in C.  One difference is that it is usually 
turned off when the function is being loaded into a package, but you can 
optionally turn it on.

You can also find out what line foo starts on, using

fooline <- getSrcLocation(foo)

This is a lot like __LINE__ in C.

Duncan Murdoch


> 
> 'getwd()' is indeed not equivalent to VBA 
> 'Application.ThisWorkbook.Path' or C macro '__FILE__' or SAS 
> %sysget(SAS_EXECFILENAME), etc.
> ------------------------------------------------------------------------
> *De :* Duncan Murdoch <murdoch.duncan using gmail.com>
> *Envoyé :* mercredi 10 octobre 2018 22:59
> *À :* Olivier GIVAUDAN; Jeff Newmiller
> *Cc :* r-help using r-project.org
> *Objet :* Re: [R] Genuine relative paths with R
> On 10/10/2018 6:52 PM, Olivier GIVAUDAN wrote:
>>>  Again, you seem to think making a package is a big deal.
>> 
>> Perhaps not a big deal (I believe you, I didn't write an R package yet), 
>> but not as straightforward as having a function within an R file 
>> returning its own path.
>> 
>>> But you're free to decide not to do it:  just please don't repeat 
>> falseclaims about R (like the ones about paths that started this long 
>> thread).
>> 
>> Which false claims?
> 
> "But I am really wondering why R doesn't have (please tell me if I'm
> wrong) this basic feature as many other languages have it (batch, shell,
> C, LaTeX, SAS with macro-variables, etc.)?"
> 
> Duncan Murdoch
> 
>> ------------------------------------------------------------------------
>> *De :* Duncan Murdoch <murdoch.duncan using gmail.com>
>> *Envoyé :* mercredi 10 octobre 2018 22:31
>> *À :* Olivier GIVAUDAN; Jeff Newmiller
>> *Cc :* r-help using r-project.org
>> *Objet :* Re: [R] Genuine relative paths with R
>> On 10/10/2018 6:17 PM, Olivier GIVAUDAN wrote:
>>>> Nothing says a package has to go on CRAN.  You can distribute 
>>> themprivately to a small audience.
>>> 
>>> Yes, I agree in theory. But this solution still violates my own 
>>> proportionality principle.
>> 
>> Again, you seem to think making a package is a big deal.  Maybe that was
>> true 10 years ago (though I wrote and tested a package in a 45 minute
>> presentation at UseR 2008), but now it's very easy.
>> 
>> But you're free to decide not to do it:  just please don't repeat false
>> claims about R (like the ones about paths that started this long thread).
>> 
>>> 
>>>> If you know as much about R as the people who wrote it
>>> 
>>> I didn't claim that (that's was a quite general / theoretical statement, 
>>> not necessarily and only applicable to R).
>> 
>> I didn't say you made that claim.  I was answering your question about
>> why inventing your own way is not a good idea.  It might be a good idea,
>> if you know the system very, very well.  Otherwise, it's probably better
>> to work the standard way.
>> 
>> Duncan Murdoch
>> 
>>> 
>>>> For example, you might thinkthat all front ends set the working 
>>> directory to the directory of theprogram they are running, because the 
>>> ones you've tried do it that way. But they don't.
>>> 
>>> It runs that way at least on Windows with RStudio and R GUI and I know 
>>> the recipients of my R code work on Windows with at least one of these 2 
>>> GUIs. So the workaround I finally found satisfies my current needs
>>> ------------------------------------------------------------------------
>>> *De :* Duncan Murdoch <murdoch.duncan using gmail.com>
>>> *Envoyé :* mercredi 10 octobre 2018 22:07
>>> *À :* Olivier GIVAUDAN; Jeff Newmiller
>>> *Cc :* r-help using r-project.org
>>> *Objet :* Re: [R] Genuine relative paths with R
>>> On 10/10/2018 5:45 PM, Olivier GIVAUDAN wrote:
>>>> I'm not sure I'm "inventing my own way" of distributing R code... And I 
>>>> distribute it to a very limited audience.
>>> 
>>> Nothing says a package has to go on CRAN.  You can distribute them
>>> privately to a small audience.
>>> 
>>>> Anyway, why not "inventing a new way" if it's more efficient than the 
>>>> standard one (I'm talking now in theory)?
>>> 
>>> If you know as much about R as the people who wrote it, then you can
>>> almost certainly invent better ways to do many of the things it does.  R
>>> Core was constrained by trying to maintain back compatibility, and that
>>> means some of their solutions aren't perfect.
>>> 
>>> But if you don't know it that well, chances are you'll make mistakes
>>> when you invent your own way of doing it.  For example, you might think
>>> that all front ends set the working directory to the directory of the
>>> program they are running, because the ones you've tried do it that way.
>>> But they don't.
>>> 
>>> Duncan Murdoch
>>> 
>>>> ------------------------------------------------------------------------
>>>> *De :* Duncan Murdoch <murdoch.duncan using gmail.com>
>>>> *Envoyé :* mercredi 10 octobre 2018 21:39
>>>> *À :* Olivier GIVAUDAN; Jeff Newmiller
>>>> *Cc :* r-help using r-project.org
>>>> *Objet :* Re: [R] Genuine relative paths with R
>>>> On 10/10/2018 5:31 PM, Olivier GIVAUDAN wrote:
>>>>> I do not want to use the terminal, just double clicks (i.e. the 
>>>>> simplest, automatic, non-manual way, without having to write a line / 
>>>>> command).
>>>>> Therefore everything should happen outside any terminal. The user won't 
>>>>> use a terminal.
>>>>> 
>>>>> I don't have a Mac and I'm not familiar with this OS, sorry.
>>>>> But I'm really surprised the click method gives different results than 
>>>>> on Linux and Windows.
>>>>> I know the click method worked both on Linux (Ubuntu latest version) and 
>>>>> Windows (10).
>>>>> 
>>>>> Yes, I executed my file from a terminal and got obviously the same 
>>>>> result as you (that's reassuring).
>>>>> 
>>>>> Come on guys, creating a package... It's like using a hammer to kill a 
>>>>> fly...
>>>> 
>>>> It's a simple operation to create a package in RStudio.  Not quite a
>>>> single click, but just a few.
>>>> 
>>>> In plain R, it's just a little more work using package.skeleton().
>>>> 
>>>> Really, if you are distributing R code, you should do it in the standard
>>>> way, not invent your own.
>>>> 
>>>> Duncan Murdoch
>>>> 
>>>>> ------------------------------------------------------------------------
>>>>> *De :* Duncan Murdoch <murdoch.duncan using gmail.com>
>>>>> *Envoyé :* mercredi 10 octobre 2018 20:54
>>>>> *À :* Olivier GIVAUDAN; Jeff Newmiller
>>>>> *Cc :* r-help using r-project.org
>>>>> *Objet :* Re: [R] Genuine relative paths with R
>>>>> On 10/10/2018 4:42 PM, Olivier GIVAUDAN wrote:
>>>>>> Why are you not simply double-clicking on 'TestPWD' and choosing to 
>>>>>> execute the file (don't add anything)?
>>>>>> Are you executing the file from a terminal?
>>>>> 
>>>>> Yes, I was executing the file from my terminal.  Otherwise I really have
>>>>> no idea what the "current directory" is in the Finder.   (I'm on a Mac.
>>>>> I just tried the click method; it printed my home directory, not the
>>>>> directory of the script.)
>>>>> 
>>>>> I don't know the name of your visual front end, but you are displaying
>>>>> the working directory that it sets when you click on TestPWD.  That will
>>>>> be different from the working directory that your user sees in the Terminal.
>>>>> 
>>>>> You can see what I saw if you run TestPWD from the Terminal.  It will
>>>>> print the current working directory, not the one where TestPWD happens
>>>>> to live.
>>>>> 
>>>>> If you want to do the same sort of thing in R, you could set up a script
>>>>> that calls R, and execute that in the way you executed TestPWD.  But in
>>>>> another message you said you aren't allowed to do that, so I think your
>>>>> best solution is the one offered by Bill Dunlap:  organize your files as
>>>>> an R package.  If you name your package "Olivier", then you can find all
>>>>> the files in it under the directory returned by
>>>>> 
>>>>>     system.file(".", package = "Olivier")
>>>>> 
>>>>> The package system is designed for R code, but you can put arbitrary
>>>>> files into a package:  just store them under the "inst" directory in
>>>>> your source.  When the package is installed, those files will be moved
>>>>> up one level, i.e.
>>>>> 
>>>>> Olivier/inst/foo
>>>>> 
>>>>> will become
>>>>> 
>>>>>     system.file("foo", package = "Olivier")
>>>>> 
>>>>> Duncan Murdoch
>>>> 
>>> 
>> 
>