[R] Genuine relative paths with R

[Ista Zahn]

Hi Oliver,

Interesting question. Can you describe your motivation in a little
more detail? That is, why do you what this feature? I ask because to
my way of thinking you have to know the path to the script in order to
call it in the first place. If calling from R, is

setwd("/path/to/dir")
source("file.R")

really so much worse than

source("path/to/dir/file.R")

?  If it is worse, why?

Similarly if calling from a shell, is

cd /path/to/dir
Rscript file.R

really so much worse than

Rscript /path/to/dir/file.R

? Again, if is worse, why?

Best,
Ista
On Sat, Oct 6, 2018 at 8:25 AM Olivier GIVAUDAN
<olivier_givaudan using hotmail.com> wrote:
>
> Dear R users,
>
> I would like to work with genuine relative paths in R for obvious reasons: if I move all my scripts related to some project as a whole to another location of my computer or someone else's computer, if want my scripts to continue to run seamlessly.
>
> What I mean by "genuine" is that it should not be necessary to hardcode one single absolute path (making the code obviously not "portable" - to another place - anymore).
>
> For the time being, I found the following related posts, unfortunately never conclusive or even somewhat off-topic:
> https://stackoverflow.com/questions/1815606/rscript-determine-path-of-the-executing-script
> https://stackoverflow.com/questions/47044068/get-the-path-of-current-script/47045368
> http://r.789695.n4.nabble.com/Script-auto-detecting-its-own-path-td2719676.html
>
> So I found 2 workarounds, more or less satisfactory:
>
>
>   1.  Either create a variable "ScriptPath" in the first lines of each of my R scripts and run a batch (or shell, etc.) to replace every single occurrence of "ScriptPath <-" by "ScriptPath <- [Absolute path of the R script]" in all the R scripts located in the folder (and possibly subfolders) of the batch file.
>   2.  Or create an R project file with RStudio and use the package "here" to get the absolute path of the R project file and put all the R scripts related to this project in the R project directory, as often recommended.
>
> 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.)?
> Do you know whether the language will have this kind of function in a near future? What are the obstacles / what is the reasoning for not having it already?
>
> Do you know other workarounds?
>
> Best regards,
>
> Olivier
>
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>
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