[R-sig-Geo] spgrass6: execGRASS: make the output of the command an R object.
Roger Bivand
Roger.Bivand at nhh.no
Mon May 20 19:38:47 CEST 2013
On Mon, 20 May 2013, Paulo van Breugel wrote:
> Hi
>
> In older version of the execGRASS function of spgrass6, setting the option
> intern=TRUE would make the output of the grass command a R object.
>
> Now, when I run execGRASS with the intern=TRUE, like the statement below,
> the output is not written to the R object.
>
> a <- execGRASS("r.univar", flags="g", map=distmod, separator=";",
> intern=TRUE)
With GRASS 6.4.2:
a <- execGRASS("r.univar", flags = "g", map = "elevation.dem", intern =
TRUE)
works as before. Adding the fs= parameter causes the failure. You are
using GRASS 7, in which fs= is separator=. In:
raster/r.univar/r.univar_main.c
only \\t, tab, space, and comma are defined as such, others seem to be
accepted, but ";" is not. I think that the parameter is unused anyway in
script-style output, but setting fs=";" certainly causes trouble.
Try without that parameter. Your observed difference in behaviour is not
intended from the R side, and is caused by odd behaviour and interaction
between parameters on the GRASS side in this GRASS module for your
parameter settings. Other GRASS modules, and r.univar with different fs=
settings, work as expected on Unix platforms, but under Windows, legacy
execution is enforced anyway.
Hope this clarifies,
Roger
>
> The object 'a' is created, but it is empty (character(0)). However, when I
> set legacyExec=TRUE (like below), the object 'a' is created with the grass
> r.univar output.
>
> a <- execGRASS("r.univar", flags="g", map=distmod, separator=";",
> legacyExec=TRUE, intern=TRUE)
>
> Is this the intended behaviour (i.e., did I miss something in the help
> file)?
>
> I am running R version 3.0.1 (2013-05-16), on Ubuntu 13.04 64-bit
>
> Paulo
>
> [[alternative HTML version deleted]]
>
> _______________________________________________
> 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, NHH Norwegian School of Economics,
Helleveien 30, N-5045 Bergen, Norway.
voice: +47 55 95 93 55; fax +47 55 95 95 43
e-mail: Roger.Bivand at nhh.no
More information about the R-sig-Geo
mailing list