[GIS] How to get started with GRASS shell

grassshell

I'm a beginner in programming but i have to work with GRASS at work, and do it quickly.

I'm completely lost with all the variety of tutorials that are existing and to me, don't look the same…and nothing of them answer my basic questions (how to make very simple loops on multiple raster).

So I want to clarify where to start and what to use. I'm using GRASS with the 6.4.2 command line, under Windows 7 OS.

I don't know if I have to use Unix syntax or other, and I don't know if I have to directly use the Python shell more than the basic grass shell.

Anybody can help me to get started with very simple tutorials for using shell (loops, work with data from mapsets, using variables, import, export…) ?

Best Answer

GRASS is written in C and have a ctypes python lib and recently an improved high level python library called pygrass. see pygrass documentation here. To work with raster data please refer to raster section of pygrass.

I would suggest you to start with python than using shell programming because all shell scripts are ported to python for cross-platform compatibility.

grass is a multi binary package. Each module runs as a separate process. To do an analysis users just call these modules with correct parameters.

These examples shows how to run grass modules by code

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[GIS] Where to change GRASS GIS wxGUI language

We have recently added a language selector in the graphical interface. This is currently under testing in GRASS 6.4.3. For now, you can upgrade to GRASS 6.4.3svn but installing this version:

http://wingrass.fsv.cvut.cz/grass64/

In the wxGUI:

Settings --> Preferences --> Appearance --> Language Settings

It should solve your problem.

GRASS GIS – GRASS Geoprocessing in Python Script

You cannot use a shapefile directly. You must first import it as a Grass layer in your mapset "Martin". A name beginning with a number (1.shp) is not allowed in Grass Also, in order to use GRASS functionality via Python from outside, some environment variables have to be set (see GRASS and Python):

after that you can use grass.script in the Python Shell:

import grass.script as grass
import grass.script.setup as gsetup
gisbase = os.environ['GISBASE']
gisdb="...your grassdata folder"
location="Martin"
mapset="PERMANENT"
gsetup.init(gisbase, gisdb, location, mymapset)
grass.run_command("v.hull", input="layer", output="layer2")
or
grass.parse_command(""v.hull", input="layer", output="layer2")

....

see GRASS Python Scripting Library or Python Scripts For GRASS GIS

Best Answer

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[GIS] Where to change GRASS GIS wxGUI language

GRASS GIS – GRASS Geoprocessing in Python Script

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