[GRASS-user] rgrass7 syntax for passing a command

GRASS GRASS user
,
1

Using GRASS 7.0.3 on Ubuntu Linux,

I'm attempting to recreate the example of r.stream.distance shown at
https://grass.osgeo.org/grass70/manuals/addons/r.stream.distance.html

by passing these comands to GRASS from within an R session. I can't figure out the correct syntax to pass this command to the system and also GRASS, any suggestions ?

The original code for GRASS command line in the example is

# Create outlet
echo "636645,218835" | v.in.ascii -n input=- output=outlet separator=","

I've tried lots of combinations of both system() and execGRASS() including this

system(message ("327500.00,523896.55") | "v.in.ascii", input="-", output="outlet", separator=",", flags=c("n", "overwrite"))

but have been unsuccessful.

Any suggestions?

Thanks, J

--
Dr. Jim Maas
Norwich Medical School

2

Hello Jim,

Maybe you should write to grass-stats mailing list, too. Perhaps someone there can provide useful insights/suggestions for your case

Best,
Vero

···

2016-04-28 12:53 GMT-03:00 Jim Maas <j.maas@uea.ac.uk>:

Using GRASS 7.0.3 on Ubuntu Linux,

I’m attempting to recreate the example of r.stream.distance shown at
https://grass.osgeo.org/grass70/manuals/addons/r.stream.distance.html

by passing these comands to GRASS from within an R session. I can’t figure out the correct syntax to pass this command to the system and also GRASS, any suggestions ?

The original code for GRASS command line in the example is

Create outlet

echo “636645,218835” | v.in.ascii -n input=- output=outlet separator=“,”

I’ve tried lots of combinations of both system() and execGRASS() including this

system(message (“327500.00,523896.55”) | “v.in.ascii”, input=“-”, output=“outlet”, separator=“,”, flags=c(“n”, “overwrite”))

but have been unsuccessful.

Any suggestions?

Thanks, J

–
Dr. Jim Maas
Norwich Medical School

grass-user mailing list
grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user

3

Hi Jim,

Although this does not solve you pipe issue (you might need to use pipe or fifo (run: help(pipe) in R for more info) :

If you just want to create a map with one point you could also use “v.edit» in non interactive mode (I guess), meaning, create a map and add a point.

Or you write your coordinates to a temporary file, which you can read in v.in.ascii

Cheers

Stefan

···

Hello Jim,

Maybe you should write to grass-stats mailing list, too. Perhaps someone there can provide useful insights/suggestions for your case

Best,

Vero

2016-04-28 12:53 GMT-03:00 Jim Maas <j.maas@uea.ac.uk>:

Using GRASS 7.0.3 on Ubuntu Linux,

I’m attempting to recreate the example of r.stream.distance shown at
https://grass.osgeo.org/grass70/manuals/addons/r.stream.distance.html

by passing these comands to GRASS from within an R session. I can’t figure out the correct syntax to pass this command to the system and also GRASS, any suggestions ?

The original code for GRASS command line in the example is

Create outlet

echo “636645,218835” | v.in.ascii -n input=- output=outlet separator=“,”

I’ve tried lots of combinations of both system() and execGRASS() including this

system(message (“327500.00,523896.55”) | “v.in.ascii”, input=“-”, output=“outlet”, separator=“,”, flags=c(“n”, “overwrite”))

but have been unsuccessful.

Any suggestions?

Thanks, J

–
Dr. Jim Maas
Norwich Medical School

grass-user mailing list
grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user

4

Simply, don't.

execGRASS() is for executing single GRASS commands, not a drop-in
replacement for bash.

Try something like creating the point in R with the correct projection, and
write that vector object to your mapset:

library(sp)
library(rgrass7)
pt <- SpatialPointsDataFrame(matrix(c(636645, 218835), ncol=2),
  proj4string=CRS(paste(execGRASS("g.proj", flags="j", intern=TRUE),
collapse=" ")),
  data=data.frame(x=1))
writeVECT(pt, "outlet")

You could create a temporary text file to read in:

tf <- tempfile()
writeLines("636645, 218835", tf)
execGRASS("v.in.ascii", input=tf, output="outlet1", separator=",",
flags="n")

which is closer to your script but less natural.

Yes, grass-stats is a more appropriate list.

Roger

-----
Roger Bivand
NHH Norwegian School of Economics, Bergen, Norway
--
View this message in context: http://osgeo-org.1560.x6.nabble.com/rgrass7-syntax-for-passing-a-command-tp5263330p5263427.html
Sent from the Grass - Users mailing list archive at Nabble.com.

5

Hi again,

On a second look I tried:

execGRASS("v.in.ascii", flags="n", input="-", output=" outlet1", Sys_input="636645|218835")

That worked for me on Ubuntu...

Cheers
Stefan

-----Original Message-----
From: grass-user [mailto:grass-user-bounces@lists.osgeo.org] On Behalf Of Roger Bivand
Sent: 29. april 2016 09:18
To: grass-user@lists.osgeo.org
Subject: Re: [GRASS-user] rgrass7 syntax for passing a command

Simply, don't.

execGRASS() is for executing single GRASS commands, not a drop-in replacement for bash.

Try something like creating the point in R with the correct projection, and write that vector object to your mapset:

library(sp)
library(rgrass7)
pt <- SpatialPointsDataFrame(matrix(c(636645, 218835), ncol=2),
  proj4string=CRS(paste(execGRASS("g.proj", flags="j", intern=TRUE), collapse=" ")),
  data=data.frame(x=1))
writeVECT(pt, "outlet")

You could create a temporary text file to read in:

tf <- tempfile()
writeLines("636645, 218835", tf)
execGRASS("v.in.ascii", input=tf, output="outlet1", separator=",",
flags="n")

which is closer to your script but less natural.

Yes, grass-stats is a more appropriate list.

Roger

-----
Roger Bivand
NHH Norwegian School of Economics, Bergen, Norway
--
View this message in context: http://osgeo-org.1560.x6.nabble.com/rgrass7-syntax-for-passing-a-command-tp5263330p5263427.html
Sent from the Grass - Users mailing list archive at Nabble.com.
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