[R-sig-Geo] warnings and errors from grass to R via spgrass6GG

[Rainer M. Krug]

Rainer at krugs.de (Rainer M. Krug) writes:

> Roger Bivand <Roger.Bivand at nhh.no> writes:
>
>> On Tue, 16 Apr 2013, Rainer M. Krug wrote:
>>
>>> Hi
>>>
>>> I am using spgrass6 with grass 7 and can report that it works so far
>>> without problems.
>>>
>>> Nevertheless, I have one question, which I already had about grass 6.
>>>
>>> I am using execGRASS to execute grass commands as well as an own defined
>>> function r.mapcalc [1].
>>>
>>> Now as these are used in a simulation script, I would like to (actually
>>> need to know) when these functions fail.
>>
>> Rainer:
>>
>> Could you please create a simple test case with some built-in data set
>> and initGRASS()? I see from ?system that some cases are addressed, but
>> with intern=TRUE.
>
> I'll investigate further and will send some examples using the spearhead
> dataset.

Hi Roger

one example is simply the following:

,----
| >  execGRASS(
|         "r.stats",
|         input = "fire_blocksgg",
|         flags = c("C", "n"),
|         intern = TRUE)
| + + + + ERROR: Raster map <fire_blocksgg> not found
| character(0)
| attr(,"status")
| [1] 1
| Warning message:
| running command 'r.stats -C -n input=fire_blocksgg' had status 1 
| > 
`----

here the error on grass side becomes translated into a warning. Changing
intern=FALSE results in no warning.

Lat me know if you would like to have more examples.

Cheers,

Rainer


>
> Thanks,
>
> Rainer
>
>>
>> Roger
>>
>>>
>>> Is there a way that errors and warnings in GRASS will be reflected as
>>> errors and warnings in R when tthe grass function is called via execGRASS?
>>>
>>> I am using Linux and R 3.0.0
>>>
>>> Thanks,
>>>
>>> Rainer
>>>
>>>
>>> Footnotes:
>>> [1] r.mapcalc is defined as follow:
>>> --8<---------------cut here---------------start------------->8---
>>> r.mapcalc <- function(
>>>    ...,
>>>    intern = TRUE,
>>>    ignore.stderr = !options("asmDebug")[[1]],
>>>    feedback = TRUE,
>>>    flags = NULL
>>>    ) {
>>>    comm <- paste( "r.mapcalc ", " \"", ..., "\" ", sep="" )
>>>    if (!is.null(flags)) {
>>>      flags <- paste0("--", flags, collapse=" ")
>>>    }
>>>    comm <- paste(comm, flags)
>>>    if (feedback) print(comm)
>>>    system( comm, intern=intern, ignore.stderr=ignore.stderr )
>>>  }
>>> --8<---------------cut here---------------end--------------->8---
>>>
>>>
>>>
>>>
>>>
>>>
> <#secure method=pgpmime mode=sign>
>
<#secure method=pgpmime mode=sign>

-- 
Rainer M. Krug, PhD (Conservation Ecology, SUN), MSc (Conservation Biology, UCT), Dipl. Phys. (Germany)

Centre of Excellence for Invasion Biology
Stellenbosch University
South Africa

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email:      Rainer at krugs.de

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