grass.script package

Python interface to launch GRASS GIS modules in scripts

Submodules

grass.script.array module

Functions to use GRASS 2D and 3D rasters with NumPy.

Usage:

>>> import grass.script as gs
>>> from grass.script import array as garray
>>>
>>> # We create a temporary region that is only valid in this python session
... gs.use_temp_region()
>>> gs.run_command("g.region", n=80, e=120, t=60, s=0, w=0, b=0, res=20, res3=20)
>>>
>>> # Lets create a raster map numpy array
... # based at the current region settings
... map2d_1 = garray.array()
>>>
>>> # Write some data
... for y in range(map2d_1.shape[0]):
...     for x in range(map2d_1.shape[1]):
...         map2d_1[y,x] = y + x
...
>>> # Lets have a look at the array
... print(map2d_1)
[[0. 1. 2. 3. 4. 5.]
 [1. 2. 3. 4. 5. 6.]
 [2. 3. 4. 5. 6. 7.]
 [3. 4. 5. 6. 7. 8.]]
>>> # This will write the numpy array as GRASS raster map
... # with name map2d_1
... map2d_1.write(mapname="map2d_1", overwrite=True)
0
>>>
>>> # We create a new array from raster map2d_1 to modify it
... map2d_2 = garray.array(mapname="map2d_1")
>>> # Don't do map2d_2 = map2d_1 % 3
... # because: this will overwrite the internal temporary filename
... map2d_2 %= 3
>>> # Show the result
... print(map2d_2)
[[0. 1. 2. 0. 1. 2.]
 [1. 2. 0. 1. 2. 0.]
 [2. 0. 1. 2. 0. 1.]
 [0. 1. 2. 0. 1. 2.]]
>>> # Write the result as new raster map with name map2d_2
... map2d_2.write(mapname="map2d_2", overwrite=True)
0
>>>
>>> # Here we create a 3D raster map numpy array
... # based in the current region settings
... map3d_1 = garray.array3d()
>>>
>>> # Write some data
... # Note: the 3D array has map[depth][row][column] order
... for z in range(map3d_1.shape[0]):
...     for y in range(map3d_1.shape[1]):
...         for x in range(map3d_1.shape[2]):
...             map3d_1[z,y,x] = z + y + x
...
>>> # Lets have a look at the 3D array
... print(map3d_1)
[[[ 0.  1.  2.  3.  4.  5.]
  [ 1.  2.  3.  4.  5.  6.]
  [ 2.  3.  4.  5.  6.  7.]
  [ 3.  4.  5.  6.  7.  8.]]
<BLANKLINE>
 [[ 1.  2.  3.  4.  5.  6.]
  [ 2.  3.  4.  5.  6.  7.]
  [ 3.  4.  5.  6.  7.  8.]
  [ 4.  5.  6.  7.  8.  9.]]
<BLANKLINE>
 [[ 2.  3.  4.  5.  6.  7.]
  [ 3.  4.  5.  6.  7.  8.]
  [ 4.  5.  6.  7.  8.  9.]
  [ 5.  6.  7.  8.  9. 10.]]]
>>> # This will write the numpy array as GRASS 3D raster map
... # with name map3d_1
... map3d_1.write(mapname="map3d_1", overwrite=True)
0
>>> # We create a new 3D array from 3D raster map3d_1 to modify it
... map3d_2 = garray.array3d(mapname="map3d_1")
>>> # Don't do map3d_2 = map3d_1 % 3
... # because: this will overwrite the internal temporary filename
... map3d_2 %= 3
>>> # Show the result
... print(map3d_2)
[[[0. 1. 2. 0. 1. 2.]
  [1. 2. 0. 1. 2. 0.]
  [2. 0. 1. 2. 0. 1.]
  [0. 1. 2. 0. 1. 2.]]
<BLANKLINE>
 [[1. 2. 0. 1. 2. 0.]
  [2. 0. 1. 2. 0. 1.]
  [0. 1. 2. 0. 1. 2.]
  [1. 2. 0. 1. 2. 0.]]
<BLANKLINE>
 [[2. 0. 1. 2. 0. 1.]
  [0. 1. 2. 0. 1. 2.]
  [1. 2. 0. 1. 2. 0.]
  [2. 0. 1. 2. 0. 1.]]]
>>> # Write the result as new 3D raster map with name map3d_2
... map3d_2.write(mapname="map3d_2", overwrite=True)
0

(C) 2010-2021 by Glynn Clements and the GRASS Development Team This program is free software under the GNU General Public License (>=v2). Read the file COPYING that comes with GRASS for details.

class grass.script.array.array

Bases: numpy.memmap

Define new numpy array

Parameters:

• cls –
• dtype – data type (default: numpy.double)
• env – environment

write(mapname, title=None, null=None, overwrite=None, quiet=None)

Write array into raster map

Parameters:

• mapname (str) – name for raster map
• title (str) – title for raster map
• null – null value
• overwrite (bool) – True for overwritting existing raster maps

Returns:

0 on success

Returns:

non-zero code on failure

class grass.script.array.array3d

Bases: numpy.memmap

Define new 3d numpy array

Parameters:

• cls –
• dtype – data type (default: numpy.double)
• env – environment

write(mapname, null=None, overwrite=None, quiet=None)

Write array into 3D raster map

Parameters:

• mapname (str) – name for 3D raster map
• null – null value
• overwrite (bool) – True for overwriting existing raster maps

Returns:

0 on success

Returns:

non-zero code on failure

grass.script.core module

Core functions to be used in Python scripts.

Usage:

from grass.script import core as grass
grass.parser()

(C) 2008-2023 by the GRASS Development Team This program is free software under the GNU General Public License (>=v2). Read the file COPYING that comes with GRASS for details.

class grass.script.core.Popen(args, **kwargs)

Bases: subprocess.Popen

grass.script.core.call(*args, **kwargs)

grass.script.core.compare_key_value_text_files(filename_a, filename_b, sep=':', val_sep=', ', precision=1e-06, proj=False, units=False)

Compare two key-value text files

This method will print a warning in case keys that are present in the first file are not present in the second one. The comparison method tries to convert the values into their native format (float, int or string) to allow correct comparison.

An example key-value text file may have this content:

a: Hello
b: 1.0
c: 1,2,3,4,5
d : hello,8,0.1

Parameters:

• filename_a (str) – name of the first key-value text file
• filenmae_b (str) – name of the second key-value text file
• sep (str) – character that separates the keys and values, default is “:”
• val_sep (str) – character that separates the values of a single key, default is “,”
• precision (double) – precision with which the floating point values are compared
• proj (bool) – True if it has to check some information about projection system
• units (bool) – True if it has to check some information about units

Returns:

True if full or almost identical, False if different

grass.script.core.create_environment(gisdbase, location, mapset)

Creates environment to be passed in run_command for example. Returns tuple with temporary file path and the environment. The user of this function is responsible for deleting the file.

grass.script.core.create_location(dbase, location, epsg=None, proj4=None, filename=None, wkt=None, datum=None, datum_trans=None, desc=None, overwrite=False)

Create new location

Raise ScriptError on error.

Parameters:

• dbase (str) – path to GRASS database
• location (str) – location name to create
• epsg – if given create new location based on EPSG code
• proj4 – if given create new location based on Proj4 definition
• filename (str) – if given create new location based on georeferenced file
• wkt (str) – if given create new location based on WKT definition (can be path to PRJ file or WKT string)
• datum – GRASS format datum code
• datum_trans – datum transformation parameters (used for epsg and proj4)
• desc – description of the location (creates MYNAME file)
• overwrite (bool) – True to overwrite location if exists(WARNING: ALL DATA from existing location ARE DELETED!)

grass.script.core.debug(msg, debug=1)

Display a debugging message using g.message -d.

The visibility of a debug message at runtime is controlled by setting the corresponding DEBUG level with g.gisenv set=”DEBUG=X” (with X set to the debug level specified in the function call).

Parameters:

• msg (str) – debugging message to be displayed
• debug (str) – debug level (0-5) with the following recommended levels: Use 1 for messages generated once of few times, 3 for messages generated for each raster row or vector line, 5 for messages generated for each raster cell or vector point.

grass.script.core.debug_level(force=False)

grass.script.core.del_temp_region()

Unsets WIND_OVERRIDE and removes any region named by it.

grass.script.core.error(msg)

Display an error message using g.message -e

This function does not end the execution of the program. The right action after the error is up to the caller. For error handling using the standard mechanism use fatal().

Parameters:msg (str) – error message to be displayed

grass.script.core.exec_command(prog, flags='', overwrite=False, quiet=False, verbose=False, superquiet=False, env=None, **kwargs)

Interface to os.execvpe(), but with the make_command() interface.

Parameters:

• prog (str) – GRASS module
• flags (str) – flags to be used (given as a string)
• overwrite (bool) – True to enable overwriting the output (<tt>–o</tt>)
• quiet (bool) – True to run quietly (<tt>–q</tt>)
• verbose (bool) – True to run verbosely (<tt>–v</tt>)
• env – directory with environmental variables
• kwargs (list) – module’s parameters

grass.script.core.fatal(msg)

Display an error message using g.message -e, then abort or raise

Raises exception when module global raise_on_error is ‘True’, abort (calls exit) otherwise. Use set_raise_on_error() to set the behavior.

Parameters:msg (str) – error message to be displayed

grass.script.core.feed_command(*args, **kwargs)

Passes all arguments to start_command(), but also adds “stdin = PIPE”. Returns the Popen object.

Parameters:

• args (list) – list of unnamed arguments (see start_command() for details)
• kwargs (list) – list of named arguments (see start_command() for details)

Returns:

Popen object

grass.script.core.find_file(name, element='cell', mapset=None, env=None)

Returns the output from running g.findfile as a dictionary. Example:

>>> result = find_file('elevation', element='cell')
>>> print(result['fullname'])
elevation@PERMANENT
>>> print(result['file'])  # doctest: +ELLIPSIS
/.../PERMANENT/cell/elevation

Parameters:

• name (str) – file name
• element (str) – element type (default ‘cell’)
• mapset (str) – mapset name (default all mapsets in search path)
• env – environment

Returns:

parsed output of g.findfile

grass.script.core.find_program(pgm, *args)

Attempt to run a program, with optional arguments.

You must call the program in a way that will return a successful exit code. For GRASS modules this means you need to pass it some valid CLI option, like “–help”. For other programs a common valid do-little option is usually “–version”.

Example:

>>> find_program('r.sun', '--help')
True
>>> find_program('ls', '--version')
True

Parameters:

• pgm (str) – program name
• args – list of arguments

Returns:

False if the attempt failed due to a missing executable or non-zero return code

Returns:

True otherwise

grass.script.core.get_capture_stderr()

Return True if stderr is captured, False otherwise.

See set_capture_stderr().

grass.script.core.get_commands()

Create list of available GRASS commands to use when parsing string from the command line

Returns:list of commands (set) and directory of scripts (collected by extension - MS Windows only)

>>> cmds = list(get_commands()[0])
>>> cmds.sort()
>>> cmds[:5]
['d.barscale', 'd.colorlist', 'd.colortable', 'd.correlate', 'd.erase']

grass.script.core.get_raise_on_error()

Return True if a ScriptError exception is raised instead of calling sys.exit(1) in case a fatal error was invoked with fatal()

grass.script.core.get_real_command(cmd)

Returns the real file command for a module (cmd)

For Python scripts on MS Windows it returns full path to the script and adds a ‘.py’ extension. For other cases it just returns a module (name). So, you can just use this function for all without further check.

>>> get_real_command('g.region')
'g.region'

Parameters:cmd – the command

grass.script.core.gisenv(env=None)

Returns the output from running g.gisenv (with no arguments), as a dictionary. Example:

>>> env = gisenv()
>>> print(env['GISDBASE'])  # doctest: +SKIP
/opt/grass-data

:param env run with different environment :return: list of GRASS variables

grass.script.core.handle_errors(returncode, result, args, kwargs)

Error handler for run_command() and similar functions

The functions which are using this function to handle errors, can be typically called with an errors parameter. This function can handle one of the following values: raise, fatal, status, exit, and ignore. The value raise is a default.

If returncode is 0, result is returned, unless errors="status" is set.

If kwargs dictionary contains key errors, the value is used to determine the return value and the behavior on error. The value errors="raise" is a default in which case a CalledModuleError exception is raised.

For errors="fatal", the function calls fatal() which has its own rules on what happens next.

For errors="status", the returncode will be returned. This is useful, e.g., for cases when the exception-based error handling mechanism is not desirable or the return code has some meaning not necessarily interpreted as an error by the caller.

For errors="exit", sys.exit() is called with the returncode, so it behaves similarly to a Bash script with set -e. No additional error message or exception is produced. This might be useful for a simple script where error message produced by the called module provides sufficient information about what happened to the end user.

Finally, for errors="ignore", the value of result will be passed in any case regardless of the returncode.

grass.script.core.info(msg)

Display an informational message using g.message -i

Parameters:msg (str) – informational message to be displayed

grass.script.core.legal_name(s)

Checks if the string contains only allowed characters.

This is the Python implementation of G_legal_filename() function.

..note:

It is not clear when exactly use this function, but it might be
useful anyway for checking map names and column names.

grass.script.core.list_grouped(type, pattern=None, check_search_path=True, exclude=None, flag='', env=None)

List of elements grouped by mapsets.

Returns the output from running g.list, as a dictionary where the keys are mapset names and the values are lists of maps in that mapset. Example:

>>> list_grouped('vect', pattern='*roads*')['PERMANENT']
['railroads', 'roadsmajor']

Parameters:

• type (str) – element type (raster, vector, raster_3d, region, …) or list of elements
• pattern (str) – pattern string
• check_search_path (str) – True to add mapsets for the search path with no found elements
• exclude (str) – pattern string to exclude maps from the research
• flag (str) – pattern type: ‘r’ (basic regexp), ‘e’ (extended regexp), or ‘’ (glob pattern)
• env – environment

Returns:

directory of mapsets/elements

grass.script.core.list_pairs(type, pattern=None, mapset=None, exclude=None, flag='', env=None)

List of elements as pairs

Returns the output from running g.list, as a list of (name, mapset) pairs

Parameters:

• type (str) – element type (raster, vector, raster_3d, region, …)
• pattern (str) – pattern string
• mapset (str) – mapset name (if not given use search path)
• exclude (str) – pattern string to exclude maps from the research
• flag (str) – pattern type: ‘r’ (basic regexp), ‘e’ (extended regexp), or ‘’ (glob pattern)
• env – environment

Returns:

list of elements

grass.script.core.list_strings(type, pattern=None, mapset=None, exclude=None, flag='', env=None)

List of elements as strings.

Returns the output from running g.list, as a list of qualified names.

Parameters:

• type (str) – element type (raster, vector, raster_3d, region, …)
• pattern (str) – pattern string
• mapset (str) – mapset name (if not given use search path)
• exclude (str) – pattern string to exclude maps from the research
• flag (str) – pattern type: ‘r’ (basic regexp), ‘e’ (extended regexp), or ‘’ (glob pattern)
• env – environment

Returns:

list of elements

grass.script.core.locn_is_latlong(env=None)

Tests if location is lat/long. Value is obtained by checking the “g.region -pu” projection code.

Returns:True for a lat/long region, False otherwise

grass.script.core.make_command(prog, flags='', overwrite=False, quiet=False, verbose=False, superquiet=False, errors=None, **options)

Return a list of strings suitable for use as the args parameter to Popen() or call(). Example:

>>> make_command("g.message", flags = 'w', message = 'this is a warning')
['g.message', '-w', 'message=this is a warning']

Parameters:

• prog (str) – GRASS module
• flags (str) – flags to be used (given as a string)
• overwrite (bool) – True to enable overwriting the output (<tt>–o</tt>)
• quiet (bool) – True to run quietly (<tt>–q</tt>)
• verbose (bool) – True to run verbosely (<tt>–v</tt>)
• options – module’s parameters

Returns:

list of arguments

grass.script.core.mapsets(search_path=False, env=None)

List available mapsets

Parameters:search_path (bool) – True to list mapsets only in search path Returns:list of mapsets

grass.script.core.message(msg, flag=None)

Display a message using g.message

Parameters:

• msg (str) – message to be displayed
• flag (str) – flags (given as string)

grass.script.core.overwrite()

Return True if existing files may be overwritten

grass.script.core.parse_color(val, dflt=None)

Parses the string “val” as a GRASS colour, which can be either one of the named colours or an R:G:B tuple e.g. 255:255:255. Returns an (r,g,b) triple whose components are floating point values between 0 and 1. Example:

>>> parse_color("red")
(1.0, 0.0, 0.0)
>>> parse_color("255:0:0")
(1.0, 0.0, 0.0)

Parameters:

• val – color value
• dflt – default color value

Returns:

tuple RGB

grass.script.core.parse_command(*args, **kwargs)

Passes all arguments to read_command, then parses the output by parse_key_val().

Parsing function can be optionally given by <em>parse</em> parameter including its arguments, e.g.

parse_command(..., parse = (grass.parse_key_val, { 'sep' : ':' }))

or you can simply define <em>delimiter</em>

parse_command(..., delimiter = ':')

Parameters:

• args – list of unnamed arguments (see start_command() for details)
• kwargs – list of named arguments (see start_command() for details)

Returns:

parsed module output

grass.script.core.parser()

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

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

Thereafter, the global variables “options” and “flags” will be dictionaries containing option/flag values, keyed by lower-case option/flag names. The values in “options” are strings, those in “flags” are Python booleans.

Overview table of parser standard options: https://grass.osgeo.org/grass-devel/manuals/parser_standard_options.html

grass.script.core.percent(i, n, s)

Display a progress info message using g.message -p

message(_("Percent complete..."))
n = 100
for i in range(n):
    percent(i, n, 1)
percent(1, 1, 1)

Parameters:

• i (int) – current item
• n (int) – total number of items
• s (int) – increment size

grass.script.core.pipe_command(*args, **kwargs)

Passes all arguments to start_command(), but also adds “stdout = PIPE”. Returns the Popen object.

>>> p = pipe_command("g.gisenv")
>>> print(p)  # doctest: +ELLIPSIS
<....Popen object at 0x...>
>>> print(p.communicate()[0])  # doctest: +SKIP
GISDBASE='/opt/grass-data';
LOCATION_NAME='spearfish60';
MAPSET='glynn';
GUI='text';
MONITOR='x0';

Parameters:

• args (list) – list of unnamed arguments (see start_command() for details)
• kwargs (list) – list of named arguments (see start_command() for details)

Returns:

Popen object

grass.script.core.read_command(*args, **kwargs)

Passes all arguments to pipe_command, then waits for the process to complete, returning its stdout (i.e. similar to shell backticks).

The behavior on error can be changed using errors parameter which is passed to the handle_errors() function.

Parameters:

• args (list) – list of unnamed arguments (see start_command() for details)
• kwargs (list) – list of named arguments (see start_command() for details)

Returns:

stdout

grass.script.core.region(region3d=False, complete=False, env=None)

Returns the output from running “g.region -gu”, as a dictionary. Example:

Parameters:

• region3d (bool) – True to get 3D region
• complete (bool) –

:param env env

>>> curent_region = region()
>>> # obtain n, s, e and w values
>>> [curent_region[key] for key in "nsew"]  # doctest: +ELLIPSIS
[..., ..., ..., ...]
>>> # obtain ns and ew resulutions
>>> (curent_region['nsres'], curent_region['ewres'])  # doctest: +ELLIPSIS
(..., ...)

Returns:dictionary of region values

grass.script.core.region_env(region3d=False, flags=None, env=None, **kwargs)

Returns region settings as a string which can used as GRASS_REGION environmental variable.

If no ‘kwargs’ are given then the current region is used. Note that this function doesn’t modify the current region!

See also use_temp_region() for alternative method how to define temporary region used for raster-based computation.

Parameters:

• region3d (bool) – True to get 3D region
• flags (string) – for example ‘a’
• env – different environment than current
• kwargs – g.region’s parameters like ‘raster’, ‘vector’ or ‘region’

os.environ['GRASS_REGION'] = grass.region_env(region='detail')
grass.mapcalc('map=1', overwrite=True)
os.environ.pop('GRASS_REGION')

Returns:string with region values Returns:empty string on error

grass.script.core.run_command(*args, **kwargs)

Execute a module synchronously

This function passes all arguments to start_command(), then waits for the process to complete. It is similar to subprocess.check_call(), but with the make_command() interface. By default, an exception is raised in case of a non-zero return code by default.

>>> run_command('g.region', raster='elevation')

See start_command() for details about parameters and usage.

The behavior on error can be changed using errors parameter which is passed to the handle_errors() function.

Parameters:

• *args –

  unnamed arguments passed to start_command()

• **kwargs –

  named arguments passed to start_command()

• errors (str) – passed to handle_errors()

Changed in version 8.0: Before 8.0, the function was returning 0 when no error occurred for backward compatibility with code which was checking that value. Now the function returns None, unless errors="status" is specified.

Changed in version 7.2: In 7.0.0, this function was returning the error code. However, it was rarely checked especially outside of the core code. Additionally, read_command() needed a mechanism to report errors as it was used more and more in context which required error handling, Thus, exceptions were introduced as a more expected default behavior for Python programmers. The change was backported to 7.0 series.

Raises:CalledModuleError when module returns non-zero return code

grass.script.core.sanitize_mapset_environment(env)

Remove environmental variables relevant only for a specific mapset. This should be called when a copy of environment is used with a different mapset.

grass.script.core.set_capture_stderr(capture=True)

Enable capturing standard error output of modules and print it.

By default, standard error output (stderr) of child processes shows in the same place as output of the parent process. This may not always be the same place as sys.stderr is written. After calling this function, functions in the grass.script package will capture the stderr of child processes and pass it to sys.stderr if there is an error.

Note

This is advantageous for interactive shells such as the one in GUI and interactive notebooks such as Jupyter Notebook.

The capturing can be applied only in certain cases, for example in case of run_command() it is applied because run_command() nor its callers do not handle the streams, however feed_command() cannot do capturing because its callers handle the streams.

The previous state is returned. Passing False disables the capturing.

New in version 7.4.

grass.script.core.set_raise_on_error(raise_exp=True)

Define behaviour on fatal error (fatal() called)

Parameters:raise_exp (bool) – True to raise ScriptError instead of calling sys.exit(1) in fatal() Returns:current status

grass.script.core.start_command(prog, flags='', overwrite=False, quiet=False, verbose=False, superquiet=False, **kwargs)

Returns a Popen object with the command created by make_command. Accepts any of the arguments which Popen() accepts apart from “args” and “shell”.

>>> p = start_command("g.gisenv", stdout=subprocess.PIPE)
>>> print(p)  # doctest: +ELLIPSIS
<...Popen object at 0x...>
>>> print(p.communicate()[0])  # doctest: +SKIP
GISDBASE='/opt/grass-data';
LOCATION_NAME='spearfish60';
MAPSET='glynn';
GUI='text';
MONITOR='x0';

If the module parameter is the same as Python keyword, add underscore at the end of the parameter. For example, use lambda_=1.6 instead of lambda=1.6.

Parameters:

• prog (str) – GRASS module
• flags (str) – flags to be used (given as a string)
• overwrite (bool) – True to enable overwriting the output (<tt>–o</tt>)
• quiet (bool) – True to run quietly (<tt>–q</tt>)
• verbose (bool) – True to run verbosely (<tt>–v</tt>)
• kwargs – module’s parameters

Returns:

Popen object

grass.script.core.tempdir(env=None)

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

grass.script.core.tempfile(create=True, env=None)

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

Parameters:

• create (bool) – True to create a file
• env – environment

Returns:

path to a tmp file

grass.script.core.tempname(length, lowercase=False)

Generate a GRASS and SQL compliant random name starting with tmp_ followed by a random part of length “length”

Parameters:

• length (int) – length of the random part of the name to generate
• lowercase (bool) – use only lowercase characters to generate name

Returns:

String with a random name of length “length” starting with a letter

Return type:

str

Example:

>>> tempname(12)
'tmp_MxMa1kAS13s9'

See also

functions append_uuid(), append_random()

grass.script.core.use_temp_region()

Copies the current region to a temporary region with “g.region save=”, then sets WIND_OVERRIDE to refer to that region. Installs an atexit handler to delete the temporary region upon termination.

grass.script.core.verbose(msg)

Display a verbose message using g.message -v

Parameters:msg (str) – verbose message to be displayed

grass.script.core.verbosity()

Return the verbosity level selected by GRASS_VERBOSE

Currently, there are 5 levels of verbosity: -1 nothing will be printed (also fatal errors and warnings will be discarded)

0 only errors and warnings are printed, triggered by “–q” or “–quiet” flag.

1 progress information (percent) and important messages will be printed

2 all messages will be printed

3 also verbose messages will be printed. Triggered by “–v” or “–verbose” flag.

grass.script.core.version()

Get GRASS version as dictionary

>>> print(version())
{'proj4': '4.8.0', 'geos': '3.3.5', 'libgis_revision': '52468',
 'libgis_date': '2012-07-27 22:53:30 +0200 (Fri, 27 Jul 2012)',
 'version': '7.0.svn', 'date': '2012', 'gdal': '2.0dev',
 'revision': '53670'}

grass.script.core.warning(msg)

Display a warning message using g.message -w

Parameters:msg (str) – warning message to be displayed

grass.script.core.write_command(*args, **kwargs)

Execute a module with standard input given by stdin parameter.

Passes all arguments to feed_command(), with the string specified by the stdin argument fed to the process’ standard input.

>>> write_command(
...    'v.in.ascii', input='-',
...    stdin='%s|%s' % (635818.8, 221342.4),
...    output='view_point')
0

See start_command() for details about parameters and usage.

The behavior on error can be changed using errors parameter which is passed to the handle_errors() function.

Parameters:

• *args –

  unnamed arguments passed to start_command()

• **kwargs –

  named arguments passed to start_command()

Returns:

0 with default parameters for backward compatibility only

Raises:

CalledModuleError when module returns non-zero return code

grass.script.db module

Database related functions to be used in Python scripts.

Usage:

from grass.script import db as grass

grass.db_describe(table)
...

(C) 2008-2015 by the GRASS Development Team This program is free software under the GNU General Public License (>=v2). Read the file COPYING that comes with GRASS for details.

grass.script.db.db_begin_transaction(driver)

Begin transaction.

Returns:SQL command as string

grass.script.db.db_commit_transaction(driver)

Commit transaction.

Returns:SQL command as string

grass.script.db.db_connection(force=False, env=None)

Return the current database connection parameters (interface to db.connect -g). Example:

>>> db_connection()
{'group': '', 'schema': '', 'driver': 'sqlite', 'database': '$GISDBASE/$LOCATION_NAME/$MAPSET/sqlite/sqlite.db'}

:param force True to set up default DB connection if not defined :param env: environment

Returns:parsed output of db.connect

grass.script.db.db_describe(table, env=None, **args)

Return the list of columns for a database table (interface to db.describe -c). Example:

>>> run_command('g.copy', vector='firestations,myfirestations')
0
>>> db_describe('myfirestations') # doctest: +ELLIPSIS
{'nrows': 71, 'cols': [['cat', 'INTEGER', '20'], ... 'ncols': 22}
>>> run_command('g.remove', flags='f', type='vector', name='myfirestations')
0

Parameters:

• table (str) – table name
• args (list) –
• env – environment

Returns:

parsed module output

grass.script.db.db_select(sql=None, filename=None, table=None, env=None, **args)

Perform SQL select statement

Note: one of <em>sql</em>, <em>filename</em>, or <em>table</em> arguments must be provided.

Examples:

>>> run_command('g.copy', vector='firestations,myfirestations')
0
>>> db_select(sql = 'SELECT cat,CITY FROM myfirestations WHERE cat < 4')
(('1', 'Morrisville'), ('2', 'Morrisville'), ('3', 'Apex'))

Simplyfied usage (it performs <tt>SELECT * FROM myfirestations</tt>.)

>>> db_select(table = 'myfirestations') # doctest: +ELLIPSIS
(('1', '24', 'Morrisville #3', ... 'HS2A', '1.37'))
>>> run_command('g.remove', flags='f', type='vector', name='myfirestations')
0

Parameters:

• sql (str) – SQL statement to perform (or None)
• filename (str) – name of file with SQL statements (or None)
• table (str) – name of table to query (or None)
• args (str) – see db.select arguments
• env – environment

grass.script.db.db_table_exist(table, env=None, **args)

Check if table exists.

If no driver or database are given, then default settings is used (check db_connection()).

>>> run_command('g.copy', vector='firestations,myfirestations')
0
>>> db_table_exist('myfirestations')
True
>>> run_command('g.remove', flags='f', type='vector', name='myfirestations')
0

Parameters:

• table (str) – table name
• args –
• env – environment

Returns:

True for success, False otherwise

grass.script.db.db_table_in_vector(table, mapset='.', env=None)

Return the name of vector connected to the table. By default it check only in the current mapset, because the same table name could be used also in other mapset by other vector. It returns None if no vectors are connected to the table.

>>> run_command('g.copy', vector='firestations,myfirestations')
0
>>> db_table_in_vector('myfirestations')
['myfirestations@user1']
>>> db_table_in_vector('mfirestations')
>>> run_command('g.remove', flags='f', type='vector', name='myfirestations')
0

Parameters:

• table (str) – name of table to query
• env – environment

grass.script.raster module

Raster related functions to be used in Python scripts.

Usage:

from grass.script import raster as grass
grass.raster_history(map)

(C) 2008-2011 by the GRASS Development Team This program is free software under the GNU General Public License (>=v2). Read the file COPYING that comes with GRASS for details.

grass.script.raster.mapcalc(exp, quiet=False, verbose=False, overwrite=False, seed=None, env=None, **kwargs)

Interface to r.mapcalc.

Parameters:

• exp (str) – expression
• quiet (bool) – True to run quietly (<tt>–q</tt>)
• verbose (bool) – True to run verbosely (<tt>–v</tt>)
• overwrite (bool) – True to enable overwriting the output (<tt>–o</tt>)
• seed – an integer used to seed the random-number generator for the rand() function, or ‘auto’ to generate a random seed
• env (dict) – dictionary of environment variables for child process
• kwargs –

grass.script.raster.mapcalc_start(exp, quiet=False, verbose=False, overwrite=False, seed=None, env=None, **kwargs)

Interface to r.mapcalc, doesn’t wait for it to finish, returns Popen object.

>>> output = 'newele'
>>> input = 'elevation'
>>> expr1 = '"%s" = "%s" * 10' % (output, input)
>>> expr2 = '...'   # etc.
>>> # launch the jobs:
>>> p1 = mapcalc_start(expr1)
>>> p2 = mapcalc_start(expr2)
...
>>> # wait for them to finish:
>>> p1.wait()
0
>>> p2.wait()
1
>>> run_command('g.remove', flags='f', type='raster', name=output)

Parameters:

• exp (str) – expression
• quiet (bool) – True to run quietly (<tt>–q</tt>)
• verbose (bool) – True to run verbosely (<tt>–v</tt>)
• overwrite (bool) – True to enable overwriting the output (<tt>–o</tt>)
• seed – an integer used to seed the random-number generator for the rand() function, or ‘auto’ to generate a random seed
• env (dict) – dictionary of environment variables for child process
• kwargs –

Returns:

Popen object

grass.script.raster.raster_history(map, overwrite=False, env=None)

Set the command history for a raster map to the command used to invoke the script (interface to r.support).

Parameters:

• map (str) – map name
• env – environment

Returns:

True on success

Returns:

False on failure

grass.script.raster.raster_info(map, env=None)

Return information about a raster map (interface to r.info -gre). Example:

>>> raster_info('elevation') # doctest: +ELLIPSIS
{'creator': '"helena"', 'cols': '1500' ... 'south': 215000.0}

Parameters:

• map (str) – map name
• env – environment

Returns:

parsed raster info

grass.script.raster.raster_what(map, coord, env=None, localized=False)

Interface to r.what

>>> raster_what('elevation', [[640000, 228000]])
[{'elevation': {'color': '255:214:000', 'label': '', 'value': '102.479'}}]

Parameters:

• map (str) – the map name
• coord (list) – a list of list containing all the point that you want query
• env –

grass.script.raster3d module

Raster3d related functions to be used in Python scripts.

Usage:

from grass.script import raster3d as grass
grass.raster3d_info(map)

(C) 2008-2016 by the GRASS Development Team This program is free software under the GNU General Public License (>=v2). Read the file COPYING that comes with GRASS for details.

grass.script.raster3d.mapcalc3d(exp, quiet=False, verbose=False, overwrite=False, seed=None, env=None, **kwargs)

Interface to r3.mapcalc.

Parameters:

• exp (str) – expression
• quiet (bool) – True to run quietly (<tt>–q</tt>)
• verbose (bool) – True to run verbosely (<tt>–v</tt>)
• overwrite (bool) – True to enable overwriting the output (<tt>–o</tt>)
• seed – an integer used to seed the random-number generator for the rand() function, or ‘auto’ to generate a random seed
• env (dict) – dictionary of environment variables for child process
• kwargs –

grass.script.raster3d.raster3d_info(map, env=None)

Return information about a raster3d map (interface to r3.info). Example:

>>> mapcalc3d('volume = row() + col() + depth()')
>>> raster3d_info('volume') # doctest: +ELLIPSIS
{'vertical_units': '"units"', 'tbres': 1.0, ... 'south': 185000.0}
>>> run_command('g.remove', flags='f', type='raster_3d', name='volume')
0

Parameters:

• map (str) – map name
• env – environment

Returns:

parsed raster3d info

grass.script.setup module

Setup, initialization, and clean-up functions

Functions can be used in Python scripts to setup a GRASS environment and session without using grassXY.

Usage:

import os
import sys
import subprocess

# define GRASS Database
# add your path to grassdata (GRASS GIS database) directory
gisdb = "~/grassdata"
# the following path is the default path on MS Windows
# gisdb = "~/Documents/grassdata"

# specify (existing) Location and Mapset
location = "nc_spm_08"
mapset = "user1"

# path to the GRASS GIS launch script
# we assume that the GRASS GIS start script is available and on PATH
# query GRASS itself for its GISBASE
# (with fixes for specific platforms)
# needs to be edited by the user
executable = "grass"
if sys.platform.startswith("win"):
    # MS Windows
    executable = r"C:\OSGeo4W\bin\grass.bat"
    # uncomment when using standalone WinGRASS installer
    # executable = r'C:\Program Files (x86)\GRASS GIS <version>\grass.bat'
    # this can be skipped if GRASS executable is added to PATH
elif sys.platform == "darwin":
    # Mac OS X
    version = "8.3"
    executable = f"/Applications/GRASS-{version}.app/Contents/Resources/bin/grass"

# query GRASS GIS itself for its Python package path
grass_cmd = [executable, "--config", "python_path"]
process = subprocess.run(grass_cmd, check=True, text=True, stdout=subprocess.PIPE)

# define GRASS-Python environment
sys.path.append(process.stdout.strip())

# import (some) GRASS Python bindings
import grass.script as gs

# launch session
session = gs.setup.init(gisdb, location, mapset)

# example calls
gs.message("Current GRASS GIS 8 environment:")
print(gs.gisenv())

gs.message("Available raster maps:")
for rast in gs.list_strings(type="raster"):
    print(rast)

gs.message("Available vector maps:")
for vect in gs.list_strings(type="vector"):
    print(vect)

# clean up at the end
session.finish()

(C) 2010-2023 by the GRASS Development Team This program is free software under the GNU General Public License (>=v2). Read the file COPYING that comes with GRASS for details.

@author Martin Landa <landa.martin gmail.com> @author Vaclav Petras <wenzeslaus gmail.com> @author Markus Metz

class grass.script.setup.SessionHandle(active=True)

Bases: object

Object used to manage GRASS sessions.

Do not create objects of this class directly. Use the init function to get a session object.

Basic usage:

# ... setup sys.path before import as needed

import grass.script as gs

session = gs.setup.init("~/grassdata/nc_spm_08/user1")

# ... use GRASS modules here

# end the session
session.finish()

Context manager usage:

# ... setup sys.path before import as needed

import grass.script as gs

with gs.setup.init("~/grassdata/nc_spm_08/user1"):
    # ... use GRASS modules here
# session ends automatically here

active

True if session is active (not finished)

finish()

Finish the session.

If not used as a context manager, call explicitly to clean and close the mapset and finish the session. No GRASS modules can be called afterwards.

grass.script.setup.call(cmd, **kwargs)

Wrapper for subprocess.call to deal with platform-specific issues

grass.script.setup.clean_default_db(*, modified_after=None)

Clean (vacuum) the default db if it is SQLite

When modified_after is set, database is cleaned only when it was modified since the modified_after time.

grass.script.setup.clean_temp()

Clean mapset temporary directory

grass.script.setup.finish(*, start_time=None)

Terminate the GRASS session and clean up

GRASS commands can no longer be used after this function has been called

Basic usage::

import grass.script as gs

gs.setup.finish()

The function is not completely symmetrical with init() because it only closes the mapset, but doesn’t undo the runtime environment setup.

When start_time is set, it might be used to determine cleaning procedures. Currently, it is used to do SQLite database vacuum only when database was modified since the session started.

grass.script.setup.get_install_path(path=None)

Get path to GRASS installation usable for setup of environmental variables.

The function tries to determine path tp GRASS GIS installation so that the returned path can be used for setup of environmental variable for GRASS runtime. If the search fails, None is returned.

By default, the resulting path is derived relatively from the location of the Python package (specifically this module) in the file system. This derived path is returned only if it has subdirectories called bin and lib. If the parameter or certain environmental variables are set, the following attempts are made to find the path.

If path is provided and it is an existing executable, the executable is queried for the path. Otherwise, provided path is returned as is.

If path is not provided, the GISBASE environmental variable is used as the path if it exists. If GRASSBIN environmental variable exists and it is an existing executable, the executable is queried for the path.

If path is not provided and no relevant environmental variables are set, the default relative path search is performed. If that fails and executable called grass exists, it is queried for the path. None is returned if all the attempts failed.

If an existing executable is called as a subprocess is called during the search and it fails, the CalledProcessError exception is propagated from the subprocess call.

grass.script.setup.init(path, location=None, mapset=None, grass_path=None)

Initialize system variables to run GRASS modules

This function is for running GRASS GIS without starting it with the standard main executable grass. No GRASS modules shall be called before call of this function but any module or user script can be called afterwards because a GRASS session has been set up. GRASS Python libraries are usable as well in general but the ones using C libraries through ctypes are not (which is caused by library path not being updated for the current process which is a common operating system limitation).

When the path or specified mapset does not exist, ValueError is raised.

The get_install_path() function is used to determine where the rest of GRASS files is installed. The grass_path parameter is passed to it if provided. If the path cannot be determined, ValueError is raised. Exceptions from the underlying function are propagated.

To create a GRASS session a session file (aka gisrc file) is created. The session object returned by this function will take care of deleting it as long as the object is used as a context manager or the finish method of the object is called explicitly. Using methods of the session object is preferred over calling the function finish().

Basic usage:

# ... setup GISBASE and sys.path before import
import grass.script as gs
session = gs.setup.init(
    "~/grassdata/nc_spm_08/user1",
    grass_path="/usr/lib/grass",
)
# ... use GRASS modules here
# end the session
session.finish()

The returned object is a context manager, so the with statement can be used to ensure that the session is finished (closed) at the end:

# ... setup sys.path before import
import grass.script as gs
with gs.setup.init("~/grassdata/nc_spm_08/user1")
    # ... use GRASS modules here

Parameters:

• path – path to GRASS database
• location – location name
• mapset – mapset within given location (default: ‘PERMANENT’)
• grass_path – path to GRASS installation or executable

Returns:

reference to a session handle object which is a context manager

grass.script.setup.set_gui_path()

Insert wxPython GRASS path to sys.path.

grass.script.setup.setup_runtime_env(gisbase)

Setup the runtime environment.

Modifies the global environment (os.environ) so that GRASS modules can run.

grass.script.setup.write_gisrc(dbase, location, mapset)

Write the gisrc file and return its path.

grass.script.task module

Get interface description of GRASS commands

Based on gui/wxpython/gui_modules/menuform.py

Usage:

from grass.script import task as gtask
gtask.command_info('r.info')

(C) 2011 by the GRASS Development Team This program is free software under the GNU General Public License (>=v2). Read the file COPYING that comes with GRASS for details.

grass.script.task.cmdlist_to_tuple(cmd)

Convert command list to tuple for run_command() and others

Parameters:cmd (list) – GRASS command to be converted Returns:command as tuple

grass.script.task.cmdstring_to_tuple(cmd)

Convert command string to tuple for run_command() and others

Parameters:cmd (str) – command to be converted Returns:command as tuple

grass.script.task.cmdtuple_to_list(cmd)

Convert command tuple to list.

Parameters:cmd (tuple) – GRASS command to be converted Returns:command in list

grass.script.task.command_info(cmd)

Returns meta information for any GRASS command as dictionary with entries for description, keywords, usage, flags, and parameters, e.g.

>>> command_info('g.tempfile') # doctest: +NORMALIZE_WHITESPACE
{'keywords': ['general', 'support'], 'params': [{'gisprompt': False,
'multiple': False, 'name': 'pid', 'guidependency': '', 'default': '',
'age': None, 'required': True, 'value': '', 'label': '', 'guisection': '',
'key_desc': [], 'values': [], 'values_desc': [], 'prompt': None,
'hidden': False, 'element': None, 'type': 'integer', 'description':
'Process id to use when naming the tempfile'}], 'flags': [{'description':
"Dry run - don't create a file, just prints it's file name", 'value':
False, 'label': '', 'guisection': '', 'suppress_required': False,
'hidden': False, 'name': 'd'}, {'description': 'Print usage summary',
'value': False, 'label': '', 'guisection': '', 'suppress_required': False,
'hidden': False, 'name': 'help'}, {'description': 'Verbose module output',
'value': False, 'label': '', 'guisection': '', 'suppress_required': False,
'hidden': False, 'name': 'verbose'}, {'description': 'Quiet module output',
'value': False, 'label': '', 'guisection': '', 'suppress_required': False,
'hidden': False, 'name': 'quiet'}], 'description': "Creates a temporary
file and prints it's file name.", 'usage': 'g.tempfile pid=integer [--help]
[--verbose] [--quiet]'}

>>> command_info('v.buffer')
['vector', 'geometry', 'buffer']

Parameters:cmd (str) – the command to query

grass.script.task.convert_xml_to_utf8(xml_text)

grass.script.task.get_interface_description(cmd)

Returns the XML description for the GRASS cmd (force text encoding to “utf-8”).

The DTD must be located in $GISBASE/gui/xml/grass-interface.dtd, otherwise the parser will not succeed.

Parameters:cmd – command (name of GRASS module)

class grass.script.task.grassTask(path=None, blackList=None)

Bases: object

This class holds the structures needed for filling by the parser

Parameter blackList is a dictionary with fixed structure, eg.

blackList = {'items' : {'d.legend' : { 'flags' : ['m'], 'params' : [] }},
             'enabled': True}

Parameters:

• path (str) – full path
• blackList – hide some options in the GUI (dictionary)

define_first()

Define first parameter

Returns:name of first parameter

get_cmd(ignoreErrors=False, ignoreRequired=False, ignoreDefault=True)

Produce an array of command name and arguments for feeding into some execve-like command processor.

Parameters:

• ignoreErrors (bool) – True to return whatever has been built so far, even though it would not be a correct command for GRASS
• ignoreRequired (bool) – True to ignore required flags, otherwise ‘@<required@>’ is shown
• ignoreDefault (bool) – True to ignore parameters with default values

get_cmd_error()

Get error string produced by get_cmd(ignoreErrors = False)

Returns:list of errors

get_description(full=True)

Get module’s description

Parameters:full (bool) – True for label + desc

get_error_msg()

Get error message (‘’ for no error)

get_flag(aFlag)

Find and return a flag by name

Raises ValueError when the flag is not found.

Parameters:aFlag (str) – name of the flag

get_keywords()

Get module’s keywords

get_list_flags(element='name')

Get list of flags

Parameters:element (str) – element name

get_list_params(element='name')

Get list of parameters

Parameters:element (str) – element name

get_name()

Get task name

get_options()

Get options

get_param(value, element='name', raiseError=True)

Find and return a param by name

Parameters:

• value – param’s value
• element (str) – element name
• raiseError (bool) – True for raise on error

has_required()

Check if command has at least one required parameter

set_flag(aFlag, aValue, element='value')

Enable / disable flag.

set_options(opts)

Set flags and parameters

:param opts list of flags and parameters

set_param(aParam, aValue, element='value')

Set param value/values.

grass.script.task.parse_interface(name, parser=<class 'grass.script.task.processTask'>, blackList=None)

Parse interface of given GRASS module

The name is either GRASS module name (of a module on path) or a full or relative path to an executable.

Parameters:

• name (str) – name of GRASS module to be parsed
• parser –
• blackList –

class grass.script.task.processTask(tree, task=None, blackList=None)

Bases: object

A ElementTree handler for the –interface-description output, as defined in grass-interface.dtd. Extend or modify this and the DTD if the XML output of GRASS’ parser is extended or modified.

Parameters:

• tree – root tree node
• task – grassTask instance or None
• blackList – list of flags/params to hide

Returns:

grassTask instance

get_task()

Get grassTask instance

grass.script.utils module

Useful functions to be used in Python scripts.

Usage:

from grass.script import utils as gutils

(C) 2014-2016 by the GRASS Development Team This program is free software under the GNU General Public License (>=v2). Read the file COPYING that comes with GRASS for details.

class grass.script.utils.KeyValue

Bases: dict

A general-purpose key-value store.

KeyValue is a subclass of dict, but also allows entries to be read and written using attribute syntax. Example:

>>> reg = KeyValue()
>>> reg['north'] = 489
>>> reg.north
489
>>> reg.south = 205
>>> reg['south']
205

grass.script.utils.append_node_pid(name)

Add node name and PID to a name (string)

For the result to be unique, the name needs to be unique within a process. Given that, the result will be unique enough for use in temporary maps and other elements on single machine or an HPC cluster.

The returned string is a name usable for vectors, tables, and columns (vector legal name) as long as provided argument name is.

>>> append_node_pid("tmp_raster_1")

..note:

Before you use this function for creating temporary files (i.e., normal
files on disk, not maps and other mapset elements), see functions
designed for it in the GRASS GIS or standard Python library. These
take care of collisions already on different levels.

grass.script.utils.append_random(name, suffix_length=None, total_length=None)

Add a random part to of a specified length to a name (string)

>>> append_random("tmp", 8)
>>> append_random("tmp", total_length=16)

..note:

Note that this will be influeced by the random seed set for the Python
random package.

..note:

See the note about creating temporary files in the
:func:`append_node_pid()` description.

grass.script.utils.append_uuid(name)

Add UUID4 to a name (string)

To generate a name of an temporary mapset element which is unique in a system, use append_node_pid() in a combination with a name unique within your process.

To avoid collisions, never shorten the name obtained from this function. A shortened UUID does not have the collision guarantees the full UUID has.

For a random name of a given shorter size, see append_random().

>>> append_uuid("tmp")

..note:

See the note about creating temporary files in the
:func:`append_node_pid()` description.

grass.script.utils.basename(path, ext=None)

Remove leading directory components and an optional extension from the specified path

Parameters:

• path (str) – path
• ext (str) – extension

grass.script.utils.clock()

Return time counter to measure performance for chunks of code. Uses time.clock() for Py < 3.3, time.perf_counter() for Py >= 3.3. Should be used only as difference between the calls.

grass.script.utils.decode(bytes_, encoding=None)

Decode bytes with default locale and return (unicode) string

No-op if parameter is not bytes (assumed unicode string).

Parameters:

• bytes (bytes) – the bytes to decode
• encoding – encoding to be used, default value is None

>>> decode(b'Südtirol')
u'Südtirol'
>>> decode(u'Südtirol')
u'Südtirol'
>>> decode(1234)
u'1234'

grass.script.utils.diff_files(filename_a, filename_b)

Diffs two text files and returns difference.

Parameters:

• filename_a (str) – first file path
• filename_b (str) – second file path

Returns:

list of strings

grass.script.utils.encode(string, encoding=None)

Encode string with default locale and return bytes with that encoding

No-op if parameter is bytes (assumed already encoded). This ensures garbage in, garbage out.

Parameters:

• string (str) – the string to encode
• encoding – encoding to be used, default value is None

>>> encode(b'Südtirol')
b'Südtirol'
>>> decode(u'Südtirol')
b'Südtirol'
>>> decode(1234)
b'1234'

grass.script.utils.float_or_dms(s)

Convert DMS to float.

>>> round(float_or_dms('26:45:30'), 5)
26.75833
>>> round(float_or_dms('26:0:0.1'), 5)
26.00003

Parameters:s – DMS value Returns:float value

grass.script.utils.get_lib_path(modname, libname=None)

Return the path of the libname contained in the module.

grass.script.utils.get_num_suffix(number, max_number)

Returns formatted number with number of padding zeros depending on maximum number, used for creating suffix for data series. Does not include the suffix separator.

Parameters:

• number – number to be formatted as map suffix
• max_number – maximum number of the series to get number of digits

>>> get_num_suffix(10, 1000)
'0010'
>>> get_num_suffix(10, 10)
'10'

grass.script.utils.legalize_vector_name(name, fallback_prefix='x')

Make name usable for vectors, tables, and columns

The returned string is a name usable for vectors, tables, and columns, i.e., it is a vector legal name which is a string containing only lowercase and uppercase ASCII letters, digits, and underscores.

Invalid characters are replaced by underscores. If the name starts with an invalid character, the name is prefixed with fallback_prefix. This increases the length of the resulting name by the length of the prefix.

The fallback_prefix can be empty which is useful when the name is later used as a suffix for some other valid name.

ValueError is raised when provided name is empty or fallback_prefix does not start with a valid character.

grass.script.utils.natural_sort(items)

Returns sorted list using natural sort (deprecated, use naturally_sorted)

grass.script.utils.naturally_sort(items, key=None)

Sorts lists using natural sort

grass.script.utils.naturally_sorted(items, key=None)

Returns sorted list using natural sort

grass.script.utils.parse_key_val(s, sep='=', dflt=None, val_type=None, vsep=None)

Parse a string into a dictionary, where entries are separated by newlines and the key and value are separated by sep (default: =)

>>> parse_key_val('min=20\nmax=50') == {'min': '20', 'max': '50'}
True
>>> parse_key_val('min=20\nmax=50',
...     val_type=float) == {'min': 20, 'max': 50}
True

Parameters:

• s (str) – string to be parsed
• sep (str) – key/value separator
• dflt – default value to be used
• val_type – value type (None for no cast)
• vsep – vertical separator (default is Python ‘universal newlines’ approach)

Returns:

parsed input (dictionary of keys/values)

grass.script.utils.separator(sep)

Returns separator from G_OPT_F_SEP appropriately converted to character.

>>> separator('pipe')
'|'
>>> separator('comma')
','

If the string does not match any of the separator keywords, it is returned as is:

>>> separator(', ')
', '

Parameters:separator (str) – character or separator keyword Returns:separator character

grass.script.utils.set_path(modulename, dirname=None, path='.')

Set sys.path looking in the the local directory GRASS directories.

Parameters:

• modulename – string with the name of the GRASS module
• dirname – string with the directory name containing the python libraries, default None
• path – string with the path to reach the dirname locally.

“set_path” example working locally with the source code of a module (r.green) calling the function with all the parameters. Below it is reported the directory structure on the r.green module.

grass_prompt> pwd
~/Download/r.green/r.green.hydro/r.green.hydro.financial

grass_prompt> tree ../../../r.green
../../../r.green
|-- ...
|-- libgreen
|   |-- pyfile1.py
|   +-- pyfile2.py
+-- r.green.hydro
   |-- Makefile
   |-- libhydro
   |   |-- pyfile1.py
   |   +-- pyfile2.py
   |-- r.green.hydro.*
   +-- r.green.hydro.financial
       |-- Makefile
       |-- ...
       +-- r.green.hydro.financial.py

21 directories, 125 files

in the source code the function is called with the following parameters:

set_path('r.green', 'libhydro', '..')
set_path('r.green', 'libgreen', os.path.join('..', '..'))

when we are executing the module: r.green.hydro.financial locally from the command line:

grass_prompt> python r.green.hydro.financial.py --ui

In this way we are executing the local code even if the module was already installed as grass-addons and it is available in GRASS standards path.

The function is cheching if the dirname is provided and if the directory exists and it is available using the path provided as third parameter, if yes add the path to sys.path to be importable, otherwise it will check on GRASS GIS standard paths.

grass.script.utils.split(s)

!Platform specific shlex.split

grass.script.utils.text_to_string(text, encoding=None)

Convert text to str. Useful when passing text into environments, in Python 2 it needs to be bytes on Windows, in Python 3 in needs unicode.

grass.script.utils.try_remove(path)

Attempt to remove a file; no exception is generated if the attempt fails.

Parameters:path (str) – path to file to remove

grass.script.utils.try_rmdir(path)

Attempt to remove a directory; no exception is generated if the attempt fails.

Parameters:path (str) – path to directory to remove

grass.script.vector module

Vector related functions to be used in Python scripts.

Usage:

from grass.script import vector as grass
grass.vector_db(map)

(C) 2008-2010 by the GRASS Development Team This program is free software under the GNU General Public License (>=v2). Read the file COPYING that comes with GRASS for details.

grass.script.vector.vector_columns(map, layer=None, getDict=True, env=None, **kwargs)

Return a dictionary (or a list) of the columns for the database table connected to a vector map (interface to v.info -c).

>>> vector_columns('geology', getDict=True) # doctest: +NORMALIZE_WHITESPACE
{'PERIMETER': {'index': 2, 'type': 'DOUBLE PRECISION'}, 'GEOL250_':
{'index': 3, 'type': 'INTEGER'}, 'SHAPE_area': {'index': 6, 'type':
'DOUBLE PRECISION'}, 'onemap_pro': {'index': 1, 'type': 'DOUBLE
PRECISION'}, 'SHAPE_len': {'index': 7, 'type': 'DOUBLE PRECISION'},
'cat': {'index': 0, 'type': 'INTEGER'}, 'GEOL250_ID': {'index': 4, 'type':
'INTEGER'}, 'GEO_NAME': {'index': 5, 'type': 'CHARACTER'}}

>>> vector_columns('geology', getDict=False) # doctest: +NORMALIZE_WHITESPACE
['cat',
 'onemap_pro',
 'PERIMETER',
 'GEOL250_',
 'GEOL250_ID',
 'GEO_NAME',
 'SHAPE_area',
 'SHAPE_len']

Parameters:

• map (str) – map name
• layer – layer number or name (None for all layers)
• getDict (bool) – True to return dictionary of columns otherwise list of column names is returned
• kwargs – (v.info’s arguments)
• env – environment

Returns:

dictionary/list of columns

grass.script.vector.vector_db(map, env=None, **kwargs)

Return the database connection details for a vector map (interface to v.db.connect -g). Example:

>>> vector_db('geology') # doctest: +ELLIPSIS, +NORMALIZE_WHITESPACE
{1: {'layer': 1, ... 'table': 'geology'}}

Parameters:

• map (str) – vector map
• kwargs – other v.db.connect’s arguments
• env – environment

Returns:

dictionary

grass.script.vector.vector_db_select(map, layer=1, env=None, **kwargs)

Get attribute data of selected vector map layer.

Function returns list of columns and dictionary of values ordered by key column value. Example:

>>> print vector_db_select('geology')['columns']
['cat', 'onemap_pro', 'PERIMETER', 'GEOL250_', 'GEOL250_ID', 'GEO_NAME', 'SHAPE_area', 'SHAPE_len']
>>> print vector_db_select('geology')['values'][3]
['3', '579286.875', '3335.55835', '4', '3', 'Zml', '579286.829631', '3335.557182']
>>> print vector_db_select('geology', columns = 'GEO_NAME')['values'][3]
['Zml']

Parameters:

• map (str) – map name
• layer (int) – layer number
• kwargs – v.db.select options
• env – environment

Returns:

dictionary (‘columns’ and ‘values’)

grass.script.vector.vector_history(map, replace=False, env=None)

Set the command history for a vector map to the command used to invoke the script (interface to v.support).

Parameters:

• map (str) – mapname
• replace (bool) – Replace command line instead of appending it
• env – environment

Returns:

v.support output

grass.script.vector.vector_info(map, layer=1, env=None)

Return information about a vector map (interface to v.info). Example:

>>> vector_info('geology') # doctest: +ELLIPSIS, +NORMALIZE_WHITESPACE
{'comment': '', 'projection': 'Lambert Conformal Conic' ... 'south': 10875.8272320917}

Parameters:

• map (str) – map name
• layer (int) – layer number
• env – environment

Returns:

parsed vector info

grass.script.vector.vector_info_topo(map, layer=1, env=None)

Return information about a vector map (interface to v.info -t). Example:

>>> vector_info_topo('geology') # doctest: +NORMALIZE_WHITESPACE
{'lines': 0, 'centroids': 1832, 'boundaries': 3649, 'points': 0,
'primitives': 5481, 'islands': 907, 'nodes': 2724, 'map3d': False,
'areas': 1832}

Parameters:

• map (str) – map name
• layer (int) – layer number
• env – environment

Returns:

parsed output

grass.script.vector.vector_layer_db(map, layer, env=None)

Return the database connection details for a vector map layer. If db connection for given layer is not defined, fatal() is called.

Parameters:

• map (str) – map name
• layer – layer number
• env – environment

Returns:

parsed output

grass.script.vector.vector_what(map, coord, distance=0.0, ttype=None, encoding=None, skip_attributes=False, layer=None, multiple=False, env=None)

Query vector map at given locations

To query one vector map at one location

print grass.vector_what(map='archsites', coord=(595743, 4925281),
                        distance=250)

[{'Category': 8, 'Map': 'archsites', 'Layer': 1, 'Key_column': 'cat',
  'Database': '/home/martin/grassdata/spearfish60/PERMANENT/dbf/',
  'Mapset': 'PERMANENT', 'Driver': 'dbf',
  'Attributes': {'str1': 'No_Name', 'cat': '8'},
  'Table': 'archsites', 'Type': 'Point', 'Id': 8}]

To query one vector map with multiple layers (no additional parameters required)

for q in grass.vector_what(map='some_map', distance=100.0,
                           coord=(596532.357143,4920486.21429)):
    print q['Map'], q['Layer'], q['Attributes']

new_bug_sites 1 {'str1': 'Beetle_site', 'GRASSRGB': '', 'cat': '80'}
new_bug_sites 2 {'cat': '80'}

To query more vector maps at one location

for q in grass.vector_what(map=('archsites', 'roads'),
                           coord=(595743, 4925281), distance=250):
    print q['Map'], q['Attributes']

archsites {'str1': 'No_Name', 'cat': '8'}
roads {'label': 'interstate', 'cat': '1'}

To query one vector map at more locations

for q in grass.vector_what(map='archsites', distance=250,
                           coord=[(595743, 4925281), (597950, 4918898)]):
    print q['Map'], q['Attributes']

archsites {'str1': 'No_Name', 'cat': '8'}
archsites {'str1': 'Bob_Miller', 'cat': '22'}

Parameters:

• map – vector map(s) to query given as string or list/tuple
• coord – coordinates of query given as tuple (easting, northing) or list of tuples
• distance – query threshold distance (in map units)
• ttype – list of topology types (default of v.what are point, line, area, face)
• encoding – attributes encoding
• skip_attributes – True to skip quering attributes
• layer – layer number or list of layers (one for each vector), if None, all layers (-1) are used
• multiple – find multiple features within threshold distance
• env – environment

Returns:

parsed list