[GRASS-stats] [R-sig-Geo] GISRC environment variable using initGRASS

Mon Apr 18 01:06:54 PDT 2016

----------------------------------------
> Date: Sun, 17 Apr 2016 20:11:06 +0200
> From: Roger.Bivand at nhh.no
> To: baerroger at outlook.com
> CC: grass-stats at lists.osgeo.org
> Subject: RE: [R-sig-Geo] GISRC environment variable using initGRASS
>
> On Sat, 16 Apr 2016, Roger Bär wrote:
>
>> Thanks for the support!Please see below my comments.
>>
>>> Date: Fri, 15 Apr 2016 20:58:15 +0200
>>> From: Roger.Bivand at nhh.no
>>> To: baerroger at outlook.com
>>> CC: r-sig-geo at r-project.org
>>> Subject: Re: [R-sig-Geo] GISRC environment variable using initGRASS
>>>
>>> On Fri, 15 Apr 2016, Roger Bär wrote:
>>>
>>>> I am currently using the R package "rgrass7" (Version: 0.1-6) in order
>>>> to command GRASS GIS (Windows7, OSGEO4W installation).
>>>>
>>>> I use R in order to start a GRASS environment and to script my
>>>> geoprocessing. Both is working fine. However, I have problems with
>>>> storing and calling the GRASS gisenv variables. Every time when I call
>>>> "initGRASS" a file called "junk" is created containing GRASS gisenv
>>>> variables.
>>>>
>>>
>>> What the file is called is probably immaterial.
>>>
>>>>
>>>> Looking at the source of the initGRASS function the section below
>>>> puzzeled me somehow:
>>>>
>>>> 59 Sys.setenv(GISRC = paste(Sys.getenv("HOME"), "\\.grassrc7",
>>>> 60 sep = ""))
>>>
>>> This is setting GISRC to a value
>>
>> Yes. The absolute path to the file (containing settings for GISDBASE,
>> LOCATION_NAME and MAPSET)
>>
>>>> 61 if (file.exists(Sys.getenv("GISRC")) && !override)
>>>> 62 stop("A GISRC file already exists; to override, set override=TRUE")
>>>> 63 Sys.setenv(GISRC = "junk")
>>>
>>> This is setting it again in the working directory - I don't recall why -
>>> probably frustration years ago with Windows.
>>
>> I really do not understand the "junk" (line 63). Because GISRC is set to
>> "junk" the subsequent lines of code will write the GISRC environment
>> variables to a newly created file called "junk" in the home folder.
>> Shouldn't this line not rather be omitted? (The GRASS environment
>> variables would then be written to ".grassrc7", which in my opinion
>> would be correct)
>
> The name of the file is immaterial, but from an R script should only be
> accessed from the value of the environment variable.
>

Ok.

>>
>>>
>>>> 64 cat("GISDBASE:", getwd(), "\n", file = Sys.getenv("GISRC"))
>>>> 65 cat("LOCATION_NAME: <UNKNOWN>", "\n", file = Sys.getenv("GISRC"),
>>>> 66 append = TRUE)
>>>> 67 cat("MAPSET: <UNKNOWN>", "\n", file = Sys.getenv("GISRC"),
>>>> 68 append = TRUE)
>>>> 69 gisrc <- ifelse(use_g.dirseps.exe, system(paste("g.dirseps.exe -g",
>>>> 70 shQuote(Sys.getenv("GISRC"))), intern = TRUE), Sys.getenv("GISRC"))
>>>> 71 assign("addEXE", .addexe(), envir = .GRASS_CACHE)
>>>> 72 Sys.setenv(GISRC = gisrc)
>>>>
>>>
>>> And this sets it again. It is set, otherwise GRASS wouldn't work;
>>> programmatically you'd have to use Sys.getenv("GISRC") to get the value.
>>> Please provide a use case where this matters, and consider moving this
>>> thread to the statsgrass list.
>>
>> Sorry, I do not understand what you mean with "provide a use case where
>> this matters". What do you mean with "this"?
>
> The use of an arbitrary name in a throw-away location is of no
> significance, and could in the future be a short random name. My guess is
> that the use of "junk" may have come from different file permissions on
> unix and windows systems - if override is TRUE, R might end up trying to
> write to a file that some other process is still blocking.
>

Ok. 

> Unless you can provide an R script that I can run in WinNat (not OSGeo4W -
> I do not have the time or patience to install multiple Windows versions of
> GRASS that I never use), and which demonstrates that something more is
> involved than the name of a temporary file, I can't help, because I do not
> see any real problem - the name if the file is arbitrary, and in the R
> session is accesses by Sys.getenv().

Ok, I get that. 
The main issue was to keept the directory clean since access my grass data from different operating system. But thinks it's not worth to spend more time on this issue. (I'll survive the junk file in my workspace)

Thanks you anyway!

Regards,
Roger  (Bä)

>> I added the thread to the grass-stat list (and will remove r-sig from
>> the cc the next time).
>
> OK,
>
> Roger (Bi)
>
>> Roger
>>
>>>
>>> Hope this helps (doesn't clarify, but that's legacy Windows),
>>>
>>> Roger
>>>
>>>> First, why is initGRASS using ".grassrc7" for storing the GISRC file?
>>>> InitGRASS is looking for the GISRC file under ".grassrc7" (line 59). However, in the package documentation [1], the GISRC file is called ".gisrc". Moreover, the GRASS documentation says that the GISRC file is stored under "/.grass7/rc"
>>>>
>>>> Second, what is the purpose of assigning "junk" to the GISRC environment variable?
>>>> GISRC is set to "junk" (line 63) and then the GISRC value ("junk") is assigned again back to system variable GISRC. Unless I misinterpreded the code, it does not make much sense to me. Shouldn't the enviroment varibales not be written (line 64 - 68) to ".grassrc7" rather than to "junk"?
>>>>
>>>>
>>>>
>>>> I would appreciate any support or hints!
>>>>
>>>> Regards,
>>>> Roger
>>>>
>>>> [1] http://https//cran.r-project.org/web/packages/rgrass7/rgrass7.pdf
>>>> [2] http://grass.osgeo.org/grass70/manuals/variables.html
>>>>
>>>> _______________________________________________
>>>> R-sig-Geo mailing list
>>>> R-sig-Geo at r-project.org
>>>> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>>>>
>>>
>>> --
>>> Roger Bivand
>>> Department of Economics, Norwegian School of Economics,
>>> Helleveien 30, N-5045 Bergen, Norway.
>>> voice: +47 55 95 93 55; fax +47 55 95 91 00
>>> e-mail: Roger.Bivand at nhh.no
>>> http://orcid.org/0000-0003-2392-6140
>>> https://scholar.google.no/citations?user=AWeghB0AAAAJ&hl=en
>>> http://depsy.org/person/434412
>>
>
> --
> Roger Bivand
> Department of Economics, Norwegian School of Economics,
> Helleveien 30, N-5045 Bergen, Norway.
> voice: +47 55 95 93 55; fax +47 55 95 91 00
> e-mail: Roger.Bivand at nhh.no
> http://orcid.org/0000-0003-2392-6140
> https://scholar.google.no/citations?user=AWeghB0AAAAJ&hl=en
> http://depsy.org/person/434412