R"""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
grass8bin = "grass"
if sys.platform.startswith("win"):
# MS Windows
grass8bin = r"C:\OSGeo4W\bin\grass.bat"
# uncomment when using standalone WinGRASS installer
# grass8bin = r'C:\Program Files (x86)\GRASS GIS 8.2.0\grass.bat'
# this can be avoided if GRASS executable is added to PATH
elif sys.platform == "darwin":
# Mac OS X
grass8bin = "/Applications/GRASS-8.2.app/Contents/Resources/bin/grass"
# query GRASS GIS itself for its Python package path
grass_cmd = [grass8bin, "--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
import grass.script.setup as gsetup
# launch session
rcfile = gsetup.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
gsetup.finish()
(C) 2010-2022 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
"""
# TODO: this should share code from lib/init/grass.py
# perhaps grass.py can import without much trouble once GISBASE
# is known, this would allow moving things from there, here
# then this could even do locking
from pathlib import Path
import os
import shutil
import subprocess
import sys
import tempfile as tmpfile
WINDOWS = sys.platform.startswith("win")
MACOS = sys.platform.startswith("darwin")
VERSION_MAJOR = "8"
VERSION_MINOR = "2"
[docs]def write_gisrc(dbase, location, mapset):
"""Write the ``gisrc`` file and return its path."""
gisrc = tmpfile.mktemp()
with open(gisrc, "w") as rc:
rc.write("GISDBASE: %s\n" % dbase)
rc.write("LOCATION_NAME: %s\n" % location)
rc.write("MAPSET: %s\n" % mapset)
return gisrc
[docs]def set_gui_path():
"""Insert wxPython GRASS path to sys.path."""
gui_path = os.path.join(os.environ["GISBASE"], "gui", "wxpython")
if gui_path and gui_path not in sys.path:
sys.path.insert(0, gui_path)
[docs]def 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.
"""
def ask_executable(arg):
"""Query the GRASS exectable for the path"""
return subprocess.run(
[arg, "--config", "path"], text=True, check=True, capture_output=True
).stdout.strip()
# Exectable was provided as parameter.
if path and shutil.which(path):
# The path was provided by the user and it is an executable
# (on path or provided with full path), so raise exception on failure.
return ask_executable(path)
# Presumably directory was provided.
if path:
return path
# GISBASE is already set.
env_gisbase = os.environ.get("GISBASE")
if env_gisbase:
return env_gisbase
# Executable provided in environment (name is from grass-session).
# The variable is supported (here), documented, but not widely promoted
# at this point (to be re-evaluated).
grass_bin = os.environ.get("GRASSBIN")
if grass_bin and shutil.which(grass_bin):
return ask_executable(grass_bin)
# Derive the path from path to this file (Python module).
# This is the standard way when there is no user-provided settings.
# Uses relative path to find the right parent and then tests presence of lib
# and bin. Removing 5 parts from the path works for
# .../grass_install_prefix/etc/python/grass and also .../python3/dist-packages/.
install_path = Path(*Path(__file__).parts[:-5])
bin_path = install_path / "bin"
lib_path = install_path / "lib"
if bin_path.is_dir() and lib_path.is_dir():
return install_path
# As a last resort, try running grass command if it exists.
# This is less likely give the right result than the relative path on systems
# with multiple installations (where an explicit setup is likely required).
# However, it allows for non-standard installations with standard command.
grass_bin = "grass"
if grass_bin and shutil.which(grass_bin):
return ask_executable(grass_bin)
return None
[docs]def setup_runtime_env(gisbase):
"""Setup the runtime environment.
Modifies the global environment (os.environ) so that GRASS modules can run.
"""
# Accept Path objects.
gisbase = os.fspath(gisbase)
# Set GISBASE
os.environ["GISBASE"] = gisbase
# define PATH
path_addition = os.pathsep + os.path.join(gisbase, "bin")
path_addition += os.pathsep + os.path.join(gisbase, "scripts")
if WINDOWS:
path_addition += os.pathsep + os.path.join(gisbase, "extrabin")
# add addons to the PATH, use GRASS_ADDON_BASE if set
# copied and simplified from lib/init/grass.py
addon_base = os.getenv("GRASS_ADDON_BASE")
if not addon_base:
if WINDOWS:
config_dirname = f"GRASS{VERSION_MAJOR}"
addon_base = os.path.join(os.getenv("APPDATA"), config_dirname, "addons")
elif MACOS:
version = f"{VERSION_MAJOR}.{VERSION_MINOR}"
addon_base = os.path.join(
os.getenv("HOME"), "Library", "GRASS", version, "Addons"
)
else:
config_dirname = f".grass{VERSION_MAJOR}"
addon_base = os.path.join(os.getenv("HOME"), config_dirname, "addons")
os.environ["GRASS_ADDON_BASE"] = addon_base
if not WINDOWS:
path_addition += os.pathsep + os.path.join(addon_base, "scripts")
path_addition += os.pathsep + os.path.join(addon_base, "bin")
os.environ["PATH"] = path_addition + os.pathsep + os.getenv("PATH")
# define LD_LIBRARY_PATH
if "LD_LIBRARY_PATH" not in os.environ:
os.environ["LD_LIBRARY_PATH"] = ""
os.environ["LD_LIBRARY_PATH"] += os.pathsep + os.path.join(gisbase, "lib")
# Set GRASS_PYTHON and PYTHONPATH to find GRASS Python modules
if not os.getenv("GRASS_PYTHON"):
if WINDOWS:
os.environ["GRASS_PYTHON"] = "python3.exe"
else:
os.environ["GRASS_PYTHON"] = "python3"
path = os.getenv("PYTHONPATH")
etcpy = os.path.join(gisbase, "etc", "python")
if path:
path = etcpy + os.pathsep + path
else:
path = etcpy
os.environ["PYTHONPATH"] = path
[docs]def 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 :func:`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.
Caller is responsible for deleting the file which is normally done
with the function :func:`finish`.
Basic usage::
# ... setup GISBASE and sys.path before import
import grass.script as gs
gs.setup.init(
"~/grassdata/nc_spm_08/user1",
grass_path="/usr/lib/grass",
)
# ... use GRASS modules here
# end the session
gs.setup.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
:param path: path to GRASS database
:param location: location name
:param mapset: mapset within given location (default: 'PERMANENT')
:param grass_path: path to GRASS installation or executable
:returns: reference to a session handle object which is a context manager
"""
grass_path = get_install_path(grass_path)
if not grass_path:
raise ValueError(
_("Parameter grass_path or GISBASE environmental variable must be set")
)
# We reduce the top-level imports because this is initialization code.
# pylint: disable=import-outside-toplevel
from grass.grassdb.checks import get_mapset_invalid_reason, is_mapset_valid
from grass.grassdb.manage import resolve_mapset_path
# Support ~ in the path for user home directory.
path = Path(path).expanduser()
# A simple existence test. The directory, whatever it is, should exist.
if not path.exists():
raise ValueError(_("Path '{path}' does not exist").format(path=path))
# A specific message when it exists, but it is a file.
if path.is_file():
raise ValueError(
_("Path '{path}' is a file, but a directory is needed").format(path=path)
)
mapset_path = resolve_mapset_path(path=path, location=location, mapset=mapset)
if not is_mapset_valid(mapset_path):
raise ValueError(
_("Mapset {path} is not valid: {reason}").format(
path=mapset_path.path,
reason=get_mapset_invalid_reason(
mapset_path.directory, mapset_path.location, mapset_path.mapset
),
)
)
setup_runtime_env(grass_path)
# TODO: lock the mapset?
os.environ["GIS_LOCK"] = str(os.getpid())
os.environ["GISRC"] = write_gisrc(
mapset_path.directory, mapset_path.location, mapset_path.mapset
)
return SessionHandle()
[docs]class SessionHandle:
"""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
import grass.script.setup
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
import grass.script.setup
with gs.setup.init("~/grassdata/nc_spm_08/user1"):
# ... use GRASS modules here
# session ends automatically here
"""
def __init__(self, active=True):
self._active = active
@property
def active(self):
"""True if session is active (not finished)"""
return self._active
def __enter__(self):
"""Enter the context manager context.
Notably, the session is activated using the *init* function.
:returns: reference to the object (self)
"""
if not self.active:
raise ValueError(
"Attempt to use inactive (finished) session as a context manager"
)
return self
def __exit__(self, type, value, traceback):
"""Exit the context manager context.
Finishes the existing session.
"""
self.finish()
[docs] def finish(self):
"""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.
"""
if not self.active:
raise ValueError("Attempt to finish an already finished session")
self._active = False
finish()
# clean-up functions when terminating a GRASS session
# these fns can only be called within a valid GRASS session
[docs]def clean_default_db():
# clean the default db if it is sqlite
from grass.script import core as gcore
from grass.script import db as gdb
conn = gdb.db_connection()
if conn and conn["driver"] == "sqlite":
# check if db exists
gisenv = gcore.gisenv()
database = conn["database"]
database = database.replace("$GISDBASE", gisenv["GISDBASE"])
database = database.replace("$LOCATION_NAME", gisenv["LOCATION_NAME"])
database = database.replace("$MAPSET", gisenv["MAPSET"])
if os.path.exists(database):
gcore.message(_("Cleaning up default sqlite database ..."))
gcore.start_command("db.execute", sql="VACUUM")
# give it some time to start
import time
time.sleep(0.1)
[docs]def call(cmd, **kwargs):
"""Wrapper for subprocess.call to deal with platform-specific issues"""
if WINDOWS:
kwargs["shell"] = True
return subprocess.call(cmd, **kwargs)
[docs]def clean_temp():
from grass.script import core as gcore
gcore.message(_("Cleaning up temporary files..."))
nul = open(os.devnull, "w")
gisbase = os.environ["GISBASE"]
call([os.path.join(gisbase, "etc", "clean_temp")], stdout=nul)
nul.close()
[docs]def finish():
"""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 :func:`init` because it only
closes the mapset, but doesn't undo the runtime environment setup.
"""
clean_default_db()
clean_temp()
# TODO: unlock the mapset?
# unset the GISRC and delete the file
from grass.script import utils as gutils
gutils.try_remove(os.environ["GISRC"])
os.environ.pop("GISRC")
# remove gislock env var (not the gislock itself
os.environ.pop("GIS_LOCK")
