>>> from env_helper import info; info()
页面更新时间: 2022-05-06 20:40:54
    Linux发行版本: Debian GNU/Linux 11 (bullseye)
    操作系统内核: Linux-5.10.0-14-amd64-x86_64-with-glibc2.31
    Python版本: 3.9.2

13.2. 使用 Python 调用 GRASS 模块

>>> import os
>>> import sys
>>> import subprocess
>>> from IPython.display import Image

gisbase 是系统中安装 GRASS 的目录

>>> gisbase = subprocess.check_output(['grass','--config','path']).decode().strip()
>>> os.environ['GISBASE'] = gisbase
>>> sys.path.append(os.path.join(gisbase,'etc','python'))
>>> import grass.script as gs
>>> import grass.script.setup as gsetup
>>> help(gsetup.init)
Help on function init in module 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.
    Caller is responsible for deleting the file which is normally done
    with the function finish().

    Basic usage::

        # ... setup GISBASE and sys.path before import
        import grass.script as gs
        # ... use GRASS modules here
        # end the session

    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


>>> gisdbase = '/home/bk/grassws'
>>> location = '/home/bk/grassws/nc_spm_08_grass7'
>>> mapset   = "user1"
>>> # os.environ['GISBASE'] = gisbase
>>> rcfile = gsetup.init(gisdbase,
>>>                      location = 'nc_spm_08_grass7',
>>>                      mapset = mapset)
>>> os.environ['GRASS_FONT']='sans'
>>> os.environ['GRASS_OVERWRITE']='1'
>>> gs.set_raise_on_error(True)
>>> gs.set_capture_stderr(True)
>>> os.environ['GRASS_RENDER_IMMEDIATE']='cairo'
>>> os.environ['GRASS_RENDER_FILE_READ']='TRUE'
>>> os.environ['GRASS_LEGEND_FILE']='legend.txt'
>>> gs.gisenv()['MAPSET']
>>> gs.parse_command('g.gisenv')
{'GISDBASE': "'/home/bk/grassws';",
 'LOCATION_NAME': "'nc_spm_08_grass7';",
 'MAPSET': "'user1';"}
>>> # gs.gisenv()['GISDBASE'] = '/home/bk/grassws';
>>> !g.gisenv
>>> gs.parse_command('g.region', region="swwake_30m", flags='pg')
{'projection': '99',
 'zone': '0',
 'n': '228500',
 's': '215000',
 'w': '630000',
 'e': '645000',
 'nsres': '30',
 'ewres': '30',
 'rows': '450',
 'cols': '500',
 'cells': '225000'}
>>> gs.run_command('d.rast', map="elevation")
>>> Image(filename="map.png")
>>> gs.run_command('d.shade', shade="elevation_shade", color="elevation", brighten="30")
>>> Image(filename="map.png")
>>> gs.parse_command('r.info', map="elevation", flags='r')
{'min': '55.57879', 'max': '156.3299'}
>>> gs.run_command('d.vect', map="streets_wake")
>>> Image(filename="map.png")