[GRASS-user] v.in.ogr in Python Grass script
Uwe Fischer
gisfisch at t-online.de
Thu Mar 3 06:57:48 PST 2016
Michel,
thank you very much for your answer. In my little script, there are more lines above that come from the wiki you referenced, too. I did not want to write them all down here in order to keep it short. Without the environment setup, I got messages like "no such module" when trying to call Grass. But that was the easier part (although hard enough for me, too :-) because I had messages.
Now the problem is that things start working (v.in) and then it crashes without any message. So I have not idea what could be wrong.
Do you really think that Grass 7 makes a diff? The menu command in 6.4.4 works fine. That's confusing to me.
Mit freundlichen Grüßen,
UWE FISCHER
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Gesendet: Donnerstag, 3. März 2016 14:31
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Betreff: grass-user Digest, Vol 119, Issue 4
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Today's Topics:
1. Change GRASS region multiple times (Luna, Daniel Eduardo)
2. Re: stream network (Stefan Lüdtke)
3. v.in.ogr in Python script not working (Uwe Fischer)
4. Re: v.in.ogr in Python script not working (Michel Wortmann)
----------------------------------------------------------------------
Message: 1
Date: Wed, 2 Mar 2016 21:40:05 +0000
From: "Luna, Daniel Eduardo" <DEL47 at pitt.edu>
To: "grass-user at lists.osgeo.org" <grass-user at lists.osgeo.org>
Cc: "Liang, Xu" <xuliang at pitt.edu>, "Hernandez Cruz, Felipe"
<FEH17 at pitt.edu>
Subject: [GRASS-user] Change GRASS region multiple times
Message-ID:
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Hello!
I'm working with pygrass, developing a new module for GRASS.
I need to create a new raster map during the execution. I'm using the commands:
from grass.pygrass import raster
newRasterMap = raster.RasterSegment('new')
newRasterMap.open('w', 'CELL')
I've noticed that new raster maps are created with the resolution of the current region in GRASS. I've noticed also that it is possible to change the current region during the execution of my new module using the script 'g.region'. However, it looks like if I want to change the resolution again, the script 'g.region' does not have any effect. My conclusion: GRASS can change the current region just 1 time during the execution of a module. Is that correct?
I would like to know how can I develop a new module (using pygrass) where I could be able to create three new raster maps with different resolutions each?
Thank you all very much!
--
Dan
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Message: 2
Date: Thu, 3 Mar 2016 10:38:42 +0100
From: Stefan Lüdtke <sluedtke at gfz-potsdam.de>
To: Janet Choate <jsc.eco at gmail.com>, Will Fields
<will.openfields at gmail.com>
Cc: grass list <grass-user at lists.osgeo.org>
Subject: Re: [GRASS-user] stream network
Message-ID: <56D80622.1070103 at gfz-potsdam.de>
Content-Type: text/plain; charset="utf-8"
Hi Janet,
can you provide a screenshot of the river network, I think that helps to understand what is going on in your specific case?!
Cheers,
Stefan
On 02/03/16 20:42, Janet Choate wrote:
> Hi Will,
> When running r.watershed on a small 35 hectare watershed, it produces
> a fully connected stream network. However, when running r.watershed on
> a
> 6400 hectare watershed, the stream network is not fully connected.
> No preprocessing with regards to merging different raster maps,
> however, I did try using r.fill.dir first to deal with any possible
> depressions that might be causing non-connected stream segments.
> thanks,
> Janet
>
> On Wed, Mar 2, 2016 at 11:22 AM, Will Fields
> <will.openfields at gmail.com <mailto:will.openfields at gmail.com>> wrote:
>
> Hi Janet,
>
> Can you give some more information about what you mean by larger
> watershed basins? Did you do any preprocessing of the elevation
> raster before you tried to extract the stream networks? Were you
> using an elevation raster that had been merged from different
> rasters? I've ran into issues in the past where "seams" along the
> original edges of a raster resulted in odd stream networks.
>
> Will
>
> On Wed, Mar 2, 2016 at 11:40 AM, Janet Choate <jsc.eco at gmail.com
> <mailto:jsc.eco at gmail.com>> wrote:
>
> Hi GRASS community,
> When creating a stream network with r.watershed, I end up with
> some isolated stream segments - particularly in larger watershed
> basins. Does anyone know how to generate a stream network that
> is fully connected, or how to correct this issue?
> thank you,
> Janet
>
>
>
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>
>
>
>
>
> --
> Tague Team Lab Manager
> 1005 Bren Hall
> UCSB, Santa Barbara, CA.
>
>
> _______________________________________________
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--
Stefan Lüdtke
Section 5.4- Hydrology
Tel.: +49 331 288 2821
Fax: +49 331 288 1570
Email: sluedtke at gfz-potsdam.de
Helmholtz-Zentrum Potsdam
Deutsches GeoForschungsZentrum GFZ
(GFZ German Research Centre for Geoscience) Stiftung des öff. Rechts Land Brandenburg Telegrafenberg, 14473 Potsdam
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Message: 3
Date: Thu, 3 Mar 2016 13:35:50 +0100
From: "Uwe Fischer" <gisfisch at t-online.de>
To: <grass-user at lists.osgeo.org>
Subject: [GRASS-user] v.in.ogr in Python script not working
Message-ID: <003f01d17549$38babe80$aa303b80$@t-online.de>
Content-Type: text/plain; charset="utf-8"
Hello,
I' new to this list and this is my first question. I try to develop a script that is able to import CAD files (MicroStation DGN) into a grass mapset.
First, I tried the command v.in.ogr in the menu system and everything works fine. The result is exactly as desired. Then, I tried to write a Python script that is able to do exactly the same but without starting GRASS.
The command line provided by the menu input (in QGIS' Grass toolbox) reads:
v.in.ogr dsn=D:/my.dgn output=gr03 type=boundary,centroid snap=0.01
min_area=1 "where="Level" = 1" -o
Searching the internet for sample scripts, I found some of those and modified my command string according to the samples:
import grass.script as grass
import grass.script.setup as gsetup
gsetup.init(gisbase,gisdbase,location,mapset)
input_dgn = "D:\\my.dgn"
grass.run_command("v.in.ogr",
dsn = input_dgn,
output = 'gr03',
type = 'boundary,centroid',
snap = 0.01,
min_area = 1,
where = """"Level" = 1""")
Unfortunately, this does not work. I get an error crash message telling me that v.in.ogr does not work any more. I tried many different options, including other use of quotes or leaving some args off. Nothing helped.
Maybe there is a keyword conflict or an issue with the order of the args?
The "where" part is very important since it helps me split the data like i need to. I use Grass 6.4.4
Thanks a lot for help an ideas,
Regards, Uwe
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Message: 4
Date: Thu, 3 Mar 2016 14:24:27 +0100
From: Michel Wortmann <wortmann at pik-potsdam.de>
To: grass-user at lists.osgeo.org
Subject: Re: [GRASS-user] v.in.ogr in Python script not working
Message-ID: <56D83B0B.4010506 at pik-potsdam.de>
Content-Type: text/plain; charset="utf-8"; Format="flowed"
Hi Uwe,
I think you are missing a few environment setup steps if you want to start your python script without starting grass. Here is all you need, although this wiki refers to GRASS7. The grass.setup.init is not enough.
https://grasswiki.osgeo.org/wiki/Working_with_GRASS_without_starting_it_explicitly
But I highly recommend upgrading to GRASS7 anyways. Only the v.in.ogr argument dsn has been changed to input.
Hope it helps.
Best,
Michel
On 03/03/2016 01:35 PM, Uwe Fischer wrote:
>
> Hello,
>
> I‘ new to this list and this is my first question. I try to develop a
> script that is able to import CAD files (MicroStation DGN) into a
> grass mapset. First, I tried the command v.in.ogr in the menu system
> and everything works fine. The result is exactly as desired. Then, I
> tried to write a Python script that is able to do exactly the same but
> without starting GRASS.
>
> The command line provided by the menu input (in QGIS‘ Grass toolbox)
> reads:
>
> v.in.ogr dsn=D:/my.dgn output=gr03 type=boundary,centroid snap=0.01
> min_area=1 "where="Level" = 1" –o
>
> Searching the internet for sample scripts, I found some of those and
> modified my command string according to the samples:
>
> import grass.script as grass
>
> import grass.script.setup as gsetup
>
> gsetup.init(gisbase,gisdbase,location,mapset)
>
> input_dgn = "D:\\my.dgn"
>
> grass.run_command("v.in.ogr",
>
> dsn = input_dgn,
>
> output = 'gr03',
>
> type = 'boundary,centroid',
>
> snap = 0.01,
>
> min_area = 1,
>
> where = """"Level" = 1""")
>
> Unfortunately, this does not work. I get an error crash message
> telling me that v.in.ogr does not work any more. I tried many
> different options, including other use of quotes or leaving some args
> off. Nothing helped. Maybe there is a keyword conflict or an issue
> with the order of the args? The „where“ part is very important since
> it helps me split the data like i need to. I use Grass 6.4.4
>
> Thanks a lot for help an ideas,
>
> Regards, Uwe
>
>
>
> _______________________________________________
> grass-user mailing list
> grass-user at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/grass-user
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