[R-sig-Geo] spgrass6, readVECT and overwriting ?

Tue Oct 27 14:11:10 CET 2015

Mathieu Rajerison <mathieu.rajerison at gmail.com> writes:

> Dear Mr Krug,
>

I'll Cc the R-sig-geo list in to keep the conversation there for future
reference and for other users who might have the same problem.

> Sorry in advance for my english.

Don't worry abut your English - it is perfectly fine.

>
> My question was not about debugging, but about a potentiel generic
> behaviour of spgrass6.
>
> I should have reformulated my question in a simpler manner : does spgrass6
> allow overwriting an existing dataset when using readVECT function ?

The functions readVect / RAST are using temporary files - you are right,
but they should delete these upon exit. So if they do nbot do this, it
is a bug.

>
> 1) no version information about R and GRASS (there are several GRASS 6
> versions)
> I've just put it at the end of this post.
> 2) no session information i.e. package versions used
> the latest spgrass6
> 3) no information about the OS (I guess it is windows based on the
> Source path above)
> you're right

OK - thanks.

> 4) no reproducible example which could be easily done by using the GRASS

As I said - if you manually have to delete the temporary files, then
there is a bug in the package. Could you please provide a reproducible
example, using one of the example data sets from GRASS, so that I can
look at it?

> 5) as far as I can see, in the newest version of spgrass6 there is no
> function readVECT()
> Yes, there is, as you will see on page 14 of the documentation.

Sorry - overlooked it.

>
> Finally, I solved the problem by using the following hint, "clean" being
> the name of my temporary shapefile dataset :
>   l = list.files("D:/GRASSDB/paca/mapset/.tmp", "^clean.*$"); l =
> file.path("D:/GRASSDB/paca/mapset/.tmp", l)
>   lapply(l,  file.remove)
>   execGRASS("v.out.ogr", parameters=list(input="clean", type="line",
> dsn="D:/GRASSDB/paca/mapset/.tmp", olayer="clean", format="ESRI_Shapefile"))

OK - reformated, the code looks as follow:

--8<---------------cut here---------------start------------->8---
l = list.files("D:/GRASSDB/paca/mapset/.tmp", "^clean.*$")
l = file.path("D:/GRASSDB/paca/mapset/.tmp", l)
lapply(l,  file.remove)
execGRASS( "v.out.ogr",
           parameters=list(input="clean", type="line",dsn="D:/GRASSDB/paca/mapset/.tmp", olayer="clean", format="ESRI_Shapefile"))
--8<---------------cut here---------------end--------------->8---

as a side note, you should be able to do

file.remove( list.files(path = "D:/GRASSDB/paca/mapset/.tmp", Pattern =
"^clean.*$", full.names = TRUE) )

or

unlink("D:/GRASSDB/paca/mapset/.tmp/clean.*")

instead of the first three commands.

Now - in your example, you don't use the readVECT() function?

If you check in the GRASS help for v.out.ogr, you can specify the
overwrite flag and the exported layer will be overwritten.

But I have the feeling you are doing something in a to complicated way.

What is it you want to do, and e=what is the problem you have or the
error message you get?

Cheers,

Rainer

>
>
>> R.Version()
> $platform
> [1] "x86_64-w64-mingw32"
> $arch
> [1] "x86_64"
> $os
> [1] "mingw32"
>
> $system
> [1] "x86_64, mingw32"
> (...)
> $version.string
> [1] "R version 3.1.2 (2014-10-31)"
> $nickname
> [1] "Pumpkin Helmet"
>
> I will happily look int this if you can provide the necessary info.
>
> Cheers,
>
> Mathieu
>
> 2015-10-24 13:34 GMT+02:00 Rainer M Krug <Rainer at krugs.de>:
>
>> Mathieu Rajerison <mathieu.rajerison at gmail.com> writes:
>>
>> > Hi,
>> >
>> > I'm using spgrass6 and I use readVECT function in a loop.
>> >
>> > Using it causes an error because it doesn't overwrite the the temporary
>> > shapefile..
>> >
>> >> thin = readVECT(vname="zoneBDTOPOthin")
>> > with_c: argument reversed from version 0.7-11 and in GRASS 6
>> > ERROR :Layer <zoneBDTO> already exists in OGR data source
>> >         'D:/GRASSDB/paca/mapset/.tmp'
>> > OGR data source with driver: ESRI Shapefile
>> > Source: "D:/GRASSDB/paca/mapset/.tmp", layer: "zoneBDTO"
>> > with 770 features
>> > It has 3 fields
>> > Warning message:
>> > running command 'v.out.ogr.exe -e -c input=zoneBDTOPOthin2 type=line
>> > layer=1 dsn=D:/GRASSDB/paca/mapset/.tmp olayer=zoneBDTO
>> > format=ESRI_Shapefile' had status 1
>> >
>> >
>> > I wonder how to specify to spgrass that I want to overwrite the file in
>> > readVECT, although I know using execGRASS and v.out.ogr with the
>> > appropriate overwrite flags would do the job.
>> >
>> > Thanks in advance for the answer..
>>
>> One reason why probably nobody replied is that
>>
>> 1) no version information about R and GRASS (there are several GRASS 6
>> versions)
>> 2) no session information i.e. package versions used
>> 3) no information about the OS (I guess it is windows based on the
>> Source path above)
>> 4) no reproducible example which could be easily done by using the GRASS
>> 5) as far as I can see, in the newest version of spgrass6 there is no
>> function readVECT()
>>
>> So I would suggest to provide the info and give a reproducible example
>> using a GRASS sample dataset
>> (see https://grass.osgeo.org/download/sample-data/ - the Spearfish
>> dataset is probably the best)
>>
>> I will happily look int this if you can provide the necessary info.
>>
>> Cheers,
>>
>> Rainer
>>
>> >
>> > Mathieu
>> >
>> >       [[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
>>
>> --
>> Rainer M. Krug, PhD (Conservation Ecology, SUN), MSc (Conservation
>> Biology, UCT), Dipl. Phys. (Germany)
>>
>> Centre of Excellence for Invasion Biology
>> Stellenbosch University
>> South Africa
>>
>> Tel :       +33 - (0)9 53 10 27 44
>> Cell:       +33 - (0)6 85 62 59 98
>> Fax :       +33 - (0)9 58 10 27 44
>>
>> Fax (D):    +49 - (0)3 21 21 25 22 44
>>
>> email:      Rainer at krugs.de
>>
>> Skype:      RMkrug
>>
>> PGP: 0x0F52F982
>>

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

Centre of Excellence for Invasion Biology
Stellenbosch University
South Africa

Tel :       +33 - (0)9 53 10 27 44
Cell:       +33 - (0)6 85 62 59 98
Fax :       +33 - (0)9 58 10 27 44

Fax (D):    +49 - (0)3 21 21 25 22 44

email:      Rainer at krugs.de

Skype:      RMkrug

PGP: 0x0F52F982
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