[R-sig-Geo] GISRC environment variable using initGRASS
Roger.Bivand at nhh.no
Fri Apr 15 20:58:15 CEST 2016
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
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
> 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.
> 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.
Hope this helps (doesn't clarify, but that's legacy Windows),
> 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 , 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!
>  http://https//cran.r-project.org/web/packages/rgrass7/rgrass7.pdf
>  http://grass.osgeo.org/grass70/manuals/variables.html
> R-sig-Geo mailing list
> R-sig-Geo at r-project.org
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
More information about the R-sig-Geo