Need help using GRASS within R - error when running the script for a second time

Dear all,

As advised by Micha (FYI his reply is at the end of this email) , I 
contact you to submit an inextricable problem when using rgrass7 : the 
script (cf. just below) works the first time but, when I rerun it a 
second time, R and windows return error messages. For this to work, I 
must close and open R or use the rs.restartR() command from RStudio, 
which is not very convenient because it stops the script.

Many thanks in advance for your help.
Lo?c

@Micha :? thank you very much for your reply. But I performed the tests 
you asked me to do and, unfortunately, none of them solve the problem. 
Also, I tried to run "execGRASS("g.proj", flags = "c", proj4 = p4str)" a 
second time WITHOUT reinitializing GRASS but R and windows still return 
the same error messages.

ERRORS WHEN I RUN THE SCRIPT FOR A SECOND TIME :

????? - FROM WINDOWS : g.region.exe : the procedure entry point GEOSMakeValid_r could not be located in the dynamic link library C:\Program Files\GRASS GIS 7.8\extrabin\gdal300.dll

????? - FROM R :
# Link to GRASS GIS software v.7.8.3

initGRASS(gisBase ="C:/Program Files/GRASS GIS 7.8",

+?????????? home="temp/GRASS_tmp", use_g.dirseps.exe=F,
+?????????? gisDbase="temp/GRASS_tmp", mapset="PERMANENT",
+?????????? remove_GISRC=T, override=T)
Error in if (is.na(projstr)) uprojargs <- projstr else uprojargs <- paste(unique(unlist(strsplit(projstr,? :
? l'argument est de longueur nulle
De plus : There were 50 or more warnings (use warnings() to see the first 50)

# Specifying the projection reference for the GRASS working environment
p4str<-sp::proj4string(seg_poly)

Warning message:
In sp::proj4string(seg_poly) :
? CRS object has comment, which is lost in output

execGRASS("g.proj", flags = "c", proj4 = p4str)
rgrass7::use_sp()

# Converting the 'sp' object into a GRASS-readable file format (here, 'vec1.shp')
writeVECT(seg_poly,"vec1",v.in.ogr_flags=c("o", "overwrite"),

+?????????? driver="ESRI Shapefile")
Error in writeVECT(seg_poly, "vec1", v.in.ogr_flags = c("o", "overwrite"),? :
? driver %in% candDrivers is not TRUE
De plus : Warning message:
In system(syscmd, intern = intern, ignore.stderr = ignore.stderr,? :
? l'ex?cution de la commande 'v.in.ogr.exe -f' renvoie un statut 313

# Run the 'v.generalize' function
execGRASS("v.generalize",flag=c("overwrite"),

+?????????? parameters=list(input="vec1",
+?????????????????????????? output="GRASS_smooth_seg_poly",
+?????????????????????????? error="GRASS_smooth_seg_poly_error",
+?????????????????????????? method="distance_weighting",
+?????????????????????????? threshold=1))

# Converting the shapefile 'GRASS_smooth_seg_poly.shp' into a R-readable object
# (here, a SpatialPolygonDataFrame named 'smooth_seg_poly')
smooth_seg_poly<-readVECT("GRASS_smooth_seg_poly", with_prj=T,

+?????????????????????????? driver="ESRI Shapefile")
Error in .read_vect_non_plugin(vname = vname, layer = layer, type = type,? :
? driver %in% candDrivers is not TRUE
De plus : Warning message:
In system(syscmd, intern = intern, ignore.stderr = ignore.stderr,? :
? l'ex?cution de la commande 'v.in.ogr.exe -f' renvoie un statut 313



REPLY FROM MICHA :
De : Micha Silver <tsvibar at gmail.com>
Envoy? : mardi 7 juillet 2020 15:55
? : Lo?c Val?ry <lvalery at outlook.fr>
Cc?: grass-user <grass-user at lists.osgeo.org>
Objet : Re: [R] Need help using GRASS within R - error when running the script for a second time
?
Hello Lo?c

Let's keep the discussion on the list, so others can help and benefit from responses.

BTW, you might want to post to the r-sig-geo list also. If you come across questions specific to R and spatial functions, that's the best place to ask.

Below,inline, some guesses as to what is happening...

On 07/07/2020 0:03, Lo?c Val?ry wrote:
initGRASS(gisBase ="C:/Program Files/GRASS GIS 7.8",

+?????????? home="temp/GRASS_tmp", use_g.dirseps.exe=F,
+?????????? gisDbase="temp/GRASS_tmp", mapset="PERMANENT",
+?????????? remove_GISRC=T, override=T)
Error in if (is.na(projstr)) uprojargs <- projstr else uprojargs <- paste(unique(unlist(strsplit(projstr,? :
? l'argument est de longueur nulle
De plus : There were 50 or more warnings (use warnings() to see the first 50)

I'm not sure, but I don't think you want to rerun initGRASS() a second time. In your script, you do initGRASS only once, then if you need to perform several analyses, do them in the same (running) GRASS session.


# Specifying the projection reference for the GRASS working environment
p4str<-sp::proj4string(seg_poly)

Warning message:
In sp::proj4string(seg_poly) :
? CRS object has comment, which is lost in output

execGRASS("g.proj", flags = "c", proj4 = p4str)
rgrass7::use_sp()

# Converting the 'sp' object into a GRASS-readable file format (here, 'vec1.shp')
writeVECT(seg_poly,"vec1",v.in.ogr_flags=c("o", "overwrite"),

+?????????? driver="ESRI Shapefile")

The driver name is "ESRI_Shapefile" (note the underscore). Perhaps that is the problem here?

Error in writeVECT(seg_poly, "vec1", v.in.ogr_flags = c("o", "overwrite"),? :
? driver %in% candDrivers is not TRUE
De plus : Warning message:
In system(syscmd, intern = intern, ignore.stderr = ignore.stderr,? :
? l'ex?cution de la commande 'v.in.ogr.exe -f' renvoie un statut 313

# Run the 'v.generalize' function
execGRASS("v.generalize",flag=c("overwrite"),

+?????????? parameters=list(input="vec1",
+?????????????????????????? output="GRASS_smooth_seg_poly",
+?????????????????????????? error="GRASS_smooth_seg_poly_error",
+?????????????????????????? method="distance_weighting",
+?????????????????????????? threshold=1))

# Converting the shapefile 'GRASS_smooth_seg_poly.shp' into a R-readable object
# (here, a SpatialPolygonDataFrame named 'smooth_seg_poly')
smooth_seg_poly<-readVECT("GRASS_smooth_seg_poly", with_prj=T,

+?????????????????????????? driver="ESRI Shapefile")

Same here, the driver name for shapefile is wrong.

I would also add that both R and GRASS have switched to the better Geopackage format for exchanging spatial data. You might want to try, the driver name is "GPKG"

See details about Geopackage here:
https://www.gis-blog.com/geopackage-vs-shapefile/
and in French here:
https://www.sigterritoires.fr/index.php/le-format-geopackage-et-qgis-3/

Best, Micha






PREVIOUS EMAILS:

De : Micha Silver <tsvibar at gmail.com>
Envoy? : mardi 9 juin 2020 23:08
? : Lo?c Val?ry <lvalery at outlook.fr>
Objet : Re: [R] Need help using GRASS within R - problem with CRS using the 'v.generalize' command
?

On 09/06/2020 16:22, Lo?c Val?ry wrote:
Dear Micha,

A thousand thanks for your help. It works now!
Whoa, you'd better save some thanks for the next question. ;-)

For your information and following your remark, I also updated rgdal.
Thanks again for taking the time to answer me.
Kind regards
Lo?c

De : Micha Silver <tsvibar at gmail.com>
Envoy? : mardi 9 juin 2020 08:44
? : Lo?c Val?ry <lvalery at outlook.fr>; r-help at R-project.org <r-help at R-project.org>
Objet : Re: [R] Need help using GRASS within R - problem with CRS using the 'v.generalize' command
?
Hello


On 08/06/2020 19:52, Lo?c Val?ry wrote:

Dear all,

First of all, this is my first message on the list. Therefore, please be indulgent if my message is not perfectly formatted as it should be.

I am currently encountering a difficulty with GRASS 7.8 within R when using the 'v.generalize' command to smooth the contour of polygons after a segmentation step.

I tried two different ways to "call" GRASS:

??????????? 1 - using the RQGIS3 package

setwd("D:/test")
library(sp)
library(rgdal)

rgdal: version: 1.4-8, (SVN revision 845)
Geospatial Data Abstraction Library extensions to R successfully loaded
Loaded GDAL runtime: GDAL 2.2.3, released 2017/11/20
Path to GDAL shared files: C:/Users/toto/Documents/R/win-library/3.6/rgdal/gdal
GDAL binary built with GEOS: TRUE
Loaded PROJ.4 runtime: Rel. 4.9.3, 15 August 2016, [PJ_VERSION: 493]
Path to PROJ.4 shared files: C:/Users/toto/Documents/R/win-library/3.6/rgdal/proj
Linking to sp version: 1.4-1

Please note that you have older versions of GDAL (2.2.3 here) and PROJ.4
(4.9 here). These are currently being replaced by GDAL 3.0 and PROJ 6.3.
You might (should) want to follow the discussion the the r-sig-geo maillist:


https://stat.ethz.ch/pipermail/r-sig-geo/2020-June/028165.html


....... (skipped all the discussion regarding RQGIS3 as I think it's not
relevant)

setwd("D:/test")
library(rgrass7)

# characteristics of the SpatialPolygonsDataFrame 'seg_poly' : CRS does exist
seg_poly

class?????? : SpatialPolygonsDataFrame
features??? : 31
extent????? : 477371.3, 477397.6, 5631995, 5632020? (xmin, xmax, ymin, ymax)
crs???????? : +proj=utm +zone=32 +datum=WGS84 +units=m +no_defs
variables?? : 1
names?????? : Seg_ID
min values? :????? 1
max values? :???? 31
Warning message:
In proj4string(x) : CRS object has comment, which is lost in output

# initialization of GRASS 7.8 from R
initGRASS(gisBase ="C:/Program Files/GRASS GIS 7.8", home="temp/GRASS",gisDbase="temp/GRASS", use_g.dirseps.exe=F,remove_GISRC=T, override=T)

gisdbase??? temp/GRASS
location??? file19685026c56
mapset????? file196829fa7141
rows??????? 1
columns???? 1
north?????? 1
south?????? 0
west??????? 0
east??????? 1
nsres?????? 1
ewres?????? 1
projection? NA

I suspect that the problem comes from 'projection NA' when initializing GRASS (cf. just above)

What you need to do here is setup the CRS of your new location.
Typically, you would run initGRASS and point to a *previously created*?
LOCATION, with CRS already defined. In this case, since you are creating
a new location, you must define it's coordinate system. (GRASS is very
"picky" about that).

Here's a GIS Stackexchange post that explains:

https://gis.stackexchange.com/questions/183032/create-a-new-grass-database-in-r-with-crs-projection


You can derive the full proj4 string from your sp object with:


p4str = sp::proj4string(seg_poly)


Then use that to set the project parameters for the new LOCATION, with

execGRASS("g.proj", flags = "c", proj4 = p4str) Now you should be able
to continue with...



execGRASS("v.generalize",flag=c("overwrite"),parameters=list(input="vec1",

+????????????????????????????????????????????????????????????? output="GRASS_smooth_seg_poly",
+????????????????????????????????????????????????????????????? error="GRASS_smooth_seg_poly_error",
+????????????????????????????????????????????????????????????? method="distance_weighting",
+????????????????????????????????????????????????????????????? threshold=1))



As a novice in the field, I would be very grateful for your help.
I remain at your entire disposal for any further information you may need to help me in finding a solution to this problem.

Yours sincerely,
Lo?c