GRASS and Python

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Revision as of 09:02, 7 August 2006 by Cmbarton (talk | contribs) (wxPython GUI development for GRASS)

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Python extensions for GRASS GIS

wxPython GUI development for GRASS

Link to wxPython prototype GUI for GRASS 6

Update 19:02, 7 August 2006 (CEST)I just uploaded a new version of and related files. I'll keep an archive and so am changing the link to go to the folder rather than the file itself so I won't have to keep changing the link. This update includes the following changes:

  • The biggest change in wrapping in This provides autogenerated wxPython GUI dialogs for all grass commands.

This can now be called from the command console (just type in the command name with no arguments as you do now) or the prototype menus. I updated to current wxPython syntax (mostly) and added methods to make it callable from other modules.

  • Methods added to and that automatically restart them with pythonw for the Mac

--Cmbarton 19:02, 7 August 2006 (CEST)

Initial development has begun on the next generation UI for GRASS. wxPython is the leading contender for a platform in which to continue development of the GRASS GUI. wxPython is a Python implementation of the well known wxWidgets (formerly wxWindows) interface development platform for C++. An initial demonstration was developed by Jachym Cepicky to show the possibility of controling GRASS via wxPython. A second generation prototype has been completed, building on Jachym's work. It is available for testing and further development at link above. --Cmbarton 07:15, 4 August 2006 (CEST)

Python-SWIG-GRASS interface

There is a prototype GRASS-SWIG interface available (thanks to Sajith VK), find it in GRASS 6-CVS: swig/python/

Background: SWIG (Simplified Wrapper and Interface Generator) is:

  • A compiler that turns ANSI C/C++ declarations into scripting language interfaces.
  • Completely automated (produces a fully working Python extension module).
  • Language neutral. SWIG can also target Tcl, Perl, Guile, MATLAB, etc...
  • Attempts to eliminate the tedium of writing extension modules.

TODO: Implement modules support in a Python class using --interface-description and a Python-XML parser. This should be a generic class with module's name as parameter, returning back an object which describes the module (description, flags, parameters, status of not/required). See GRASS 6 wxPython interface for inspiration. Important is to auto-generate the GRASS-Python class at compile time with a Python script.

Python-GRASS add-ons

Stand-alone addons:

  1. Jáchym Čepický's, a GUI to typeset printable maps with (
  2. Jáchym Čepický's v.pydigit, a GUI to v.edit (
  3. Jáchym Čepický's PyWPS, GRASS-Web Processing Service (

Using Grass gui.tcl in python

Here is some example code to use the grass automatically generated guis in python code. This could (should) all be bundled up and abstracted away so that the implementation can be replaced later.

import Tkinter
import os

# Startup (once):

tk = Tkinter.Tk()
tk.eval ("wm withdraw .")
tk.eval ("source $env(GISBASE)/etc/gui.tcl")
# Here you could do various things to change what the gui does
# See gui.tcl and README.GUI

# Make a gui (per dialog)
# This sets up a window for the command.
# This can be different to integrate with tkinter:
tk.eval ('set path ".dialog$dlg"')
tk.eval ('toplevel .dialog$dlg')
# Load the code for this command:
fd = os.popen ("d.vect --tcltk")
gui =
# Run it
dlg = tk.eval('set dlg') # This is used later to get and set 

# Get the current command in the gui we just made:
currentcommand = tk.eval ("dialog_get_command " + dlg)

# Set the command in the dialog we just made:
tk.eval ("dialog_set_command " + dlg + " {d.vect map=roads}")