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
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 = "8.5"
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) 2010-2024 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 datetime
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 = "5"
[docs]def write_gisrc(dbase, location, mapset):
"""Write the ``gisrc`` file and return its path."""
with tmpfile.NamedTemporaryFile(mode="w", delete=False) as rc:
gisrc = rc.name
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 executable for the path"""
return subprocess.run(
[arg, "--config", "path"], text=True, check=True, capture_output=True
).stdout.strip()
# Executable 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=None, *, env=None):
"""Setup the runtime environment.
Modifies environment so that GRASS modules can run. It does not setup a session,
but only the system environment to execute commands.
Modifies the environment provided with _env_. If _env_ is not
provided, modifies the global environment (os.environ). Pass a copy of the
environment if you don't want the source environment modified.
If _gisbase_ is not provided, a heuristic is used to find the path to GRASS
installation (see the :func:`get_install_path` function for details).
"""
if not gisbase:
gisbase = get_install_path()
# Accept Path objects.
gisbase = os.fspath(gisbase)
# If environment is not provided, use the global one.
if not env:
env = os.environ
from grass.app.runtime import (
get_grass_config_dir,
set_dynamic_library_path,
set_executable_paths,
set_path_to_python_executable,
set_python_path_variable,
)
# Set GISBASE
env["GISBASE"] = gisbase
set_executable_paths(
install_path=gisbase,
grass_config_dir=get_grass_config_dir(VERSION_MAJOR, VERSION_MINOR, env=env),
env=env,
)
set_dynamic_library_path(
variable_name="LD_LIBRARY_PATH", install_path=gisbase, env=env
)
set_python_path_variable(install_path=gisbase, env=env)
set_path_to_python_executable(env=env)
[docs]def init(path, location=None, mapset=None, *, grass_path=None, env=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.
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 :func:`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
: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
"""
# The path heuristic always uses the global environment.
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
),
)
)
# If environment is not provided, use the global one.
if not env:
env = os.environ
setup_runtime_env(grass_path, env=env)
# TODO: lock the mapset?
env["GIS_LOCK"] = str(os.getpid())
env["GISRC"] = write_gisrc(
mapset_path.directory, mapset_path.location, mapset_path.mapset
)
return SessionHandle(env=env)
[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
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
The example above is modifying the global, process environment (`os.environ`).
If you don't want to modify the global environment, use the _env_ parameter
for the _init_ function to modify the provided environment instead.
This environment is then available as an attribute of the session object.
The attribute then needs to be passed to all calls of GRASS
tools and functions that wrap them.
Context manager usage with custom environment::
# ... setup sys.path before import as needed
import grass.script as gs
with gs.setup.init("~/grassdata/nc_spm_08/user1", env=os.environ.copy()):
# ... use GRASS modules here with env parameter
gs.run_command("g.region", flags="p", env=session.env)
# session ends automatically here, global environment was never modifed
"""
def __init__(self, *, env, active=True):
self._env = env
self._active = active
self._start_time = datetime.datetime.now(datetime.timezone.utc)
@property
def active(self):
"""True if session is active (not finished)"""
return self._active
@property
def env(self):
return self._env
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:
msg = "Attempt to use inactive (finished) session as a context manager"
raise ValueError(msg)
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:
msg = "Attempt to finish an already finished session"
raise ValueError(msg)
self._active = False
finish(env=self._env, start_time=self._start_time)
# clean-up functions when terminating a GRASS session
# these fns can only be called within a valid GRASS session
[docs]def clean_default_db(*, modified_after=None, env=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.
"""
# Limiting usage of in other function by lazy-imports.
# pylint: disable=import-outside-toplevel
import grass.script as gs
conn = gs.db_connection(env=env)
if not conn or conn["driver"] != "sqlite":
return
# check if db exists
gis_env = gs.gisenv(env=env)
database = conn["database"]
database = database.replace("$GISDBASE", gis_env["GISDBASE"])
database = database.replace("$LOCATION_NAME", gis_env["LOCATION_NAME"])
database = database.replace("$MAPSET", gis_env["MAPSET"])
database = Path(database)
if not database.is_file():
return
file_stat = database.stat()
# Small size based on MEMORYMB (MiB) or its default.
small_db_size = int(gis_env.get("MEMORYMB", 300)) * (1 << 20)
if file_stat.st_size <= small_db_size:
return
if modified_after:
modified_time = datetime.datetime.fromtimestamp(
file_stat.st_mtime, tz=datetime.timezone.utc
)
if modified_after >= modified_time:
return
# Start the vacuum process, then show the message in parallel while
# the vacuum is running. Finally, wait for the vacuum process to finish.
# Error handling is the same as errors="ignore".
process = gs.start_command("db.execute", sql="VACUUM", env=env)
gs.verbose(_("Cleaning up SQLite attribute database..."), env=env)
process.wait()
[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(env=None):
"""Clean mapset temporary directory"""
# Lazy-importing to reduce dependencies (this can be eventually removed).
# pylint: disable=import-outside-toplevel
import grass.script as gs
if not env:
env = os.environ
gs.verbose(_("Cleaning up temporary files..."), env=env)
gisbase = env["GISBASE"]
call(
[os.path.join(gisbase, "etc", "clean_temp")], stdout=subprocess.DEVNULL, env=env
)
[docs]def finish(*, env=None, 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 :func:`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.
"""
if not env:
env = os.environ
clean_default_db(modified_after=start_time, env=env)
clean_temp(env=env)
# TODO: unlock the mapset?
# unset the GISRC and delete the file
from grass.script import utils as gutils
gutils.try_remove(env["GISRC"])
del env["GISRC"]
# remove gislock env var (not the gislock itself
del env["GIS_LOCK"]
