GRASS Python Scripting Library

by GRASS Development Team (http://grass.osgeo.org)

Introduction

The code in lib/python/ provides grass.script in order to support GRASS scripts written in Python. The scripts/ directory of GRASS contains a series of examples actually provided to the end users.

See code in:

• core.py
• db.py
• raster.py
• vector.py

Table of content

• GRASS scripting tasks for Python provided by "grass.script"
• List of modules
  • Core
  • Database
  • Raster
  • Vector

GRASS scripting tasks for Python provided by "grass.script"

Usage:

import grass.script as grass

or just import selected module, e.g.

from grass.script import core as grass

Sample script

#!/usr/bin/env python

#%module
#% description: Checks if vector map is 3D
#% keywords: vector
#%end
#%option
#% key: map
#% type: string
#% gisprompt: old,vector,vector
#% key_desc: name
#% description: Name of vector map 
#% required: yes
#%end

import sys
import grass.script as grass

def main():
    info = grass.parse_command('v.info',
                               flags = 't',
                               map = options['map'])
    if info['map3d'] == '1':
        print 'Vector map is 3D'
    else:
        print 'Vector map is 2D'

    return 0

if __name__ == "__main__":
    options, flags = grass.parser()
    sys.exit(main())

List of modules

Core

GRASS-oriented interface to subprocess module

• exec_command()

• feed_command()

• make_command()

• parse_command()

• pipe_command()

• read_command()

• run_command()

• start_command()

• write_command()

Interface to g.message

These all run g.message, differing only in which flag (if any) is used. fatal() is error(), but also calls sys.exit(1).

• debug()

• error()

• fatal()

• info()

• message()

• verbose()

• warning()

Interface to g.parser

Interface to g.parser, intended to be run from the top-level, e.g.

        if __name__ == "__main__":
            options, flags = grass.parser()
            main()

• parser()

Interface to g.tempfile

Returns the name of a temporary file, created with g.tempfile.

• tempfile()

Key-value parsers

• parse_key_val()

Interface to g.gisenv

• gisenv()

Interface to g.region

• del_temp_region()

• region()

• use_temp_region()

Interface to g.findfile

• find_file()

Interface to g.list

• list_grouped()

• list_pairs()

• list_strings()

• mlist_grouped()

Color parsing

• parse_color()

Check GRASS environment variables

• overwrite()

• verbosity()

Various utilities, not specific to GRASS

• basename()

• find_program()

• try_remove()

• try_rmdir()

• float_or_dms()

Database

Interface for db.* modules.

from grass.script import db as grass

• db_connection()

• db_describe()

• db_select()

Raster

Interface for r.* modules.

from grass.script import raster as grass

• raster_history()

• raster_info()

• mapcalc()

Vector

Interface for v.* modules.

from grass.script import vector as grass

• vector_columns()

• vector_db()

• vector_db_select()

• vector_history()

• vector_info_topo()

• vector_layer_db()

Authors

Glynn Clements

Martin Landa <landa.martin gmail.com>