Shapely Geospatial geometries, predicates, and operations Shapely ======= Shapely is a Python package for programming with 2D geospatial geometries. It is based on GEOS (http://geos.refractions.net). Shapely 1.0 is ignorant about coordinate and reference systems. Projection responsibility is left to specific applications. For more information, see: * Shapely wiki_ * Shapely manual_ Shapely requires Python 2.4+. (I've also begun to port it to Python 3.0: http://zcologia.com/news/564/shapely-for-python-3-0/.) Dependencies ------------ * libgeos_c (2.2.3 or 3.0.0+) * Python ctypes_ (standard in Python 2.5+) .. _ctypes: http://pypi.python.org/pypi/ctypes/ Installation ------------ Windows users should use the executable installer, which contains the required GEOS DLL. Other users should acquire libgeos_c by any means, make sure that it is on the system library path, and install from the Python package index:: $ sudo easy_install Shapely with the setup script:: $ sudo python setup.py install or by using the development buildout on Linux, which also provides libgeos_c:: $ svn co http://svn.gispython.org/svn/gispy/buildout/shapely.buildout/trunk shapely.buildout $ cd shapely.buildout $ python bootstrap.py $ ./bin/buildout Usage ----- To buffer a point:: >>> from shapely.geometry import Point >>> point = Point(-106.0, 40.0) # longitude, latitude >>> point.buffer(10.0) <shapely.geometry.polygon.Polygon object at ...> See the manual_ for comprehensive examples of usage. See also Operations.txt and Predicates.txt under tests/ for more examples of the spatial operations and predicates provided by Shapely. See also Point.txt, LineString.txt, etc for examples of the geometry APIs. Numpy integration ----------------- All Shapely geometry instances provide the Numpy array interface:: >>> from numpy import asarray >>> a = asarray(point) >>> a.size 3 >>> a.shape (2,) Numpy arrays can also be adapted to Shapely points and linestrings:: >>> from shapely.geometry import asLineString >>> a = array([[1.0, 2.0], [3.0, 4.0]]) >>> line = asLineString(a) >>> line.wkt 'LINESTRING (1.0000000000000000 2.0000000000000000, 3.0000000000000000 4.0000000000000000)' Python Geo Interface -------------------- Any object that provides the Python geo interface can be adapted to a Shapely geometry with the asShape factory:: >>> d = {"type": "Point", "coordinates": (0.0, 0.0)} >>> from shapely.geometry import asShape >>> shape = asShape(d) >>> shape.geom_type 'Point' >>> tuple(shape.coords) ((0.0, 0.0),) >>> class GeoThing(object): ... def __init__(self, d): ... self.__geo_interface__ = d >>> thing = GeoThing({"type": "Point", "coordinates": (0.0, 0.0)}) >>> shape = asShape(thing) >>> shape.geom_type 'Point' >>> tuple(shape.coords) ((0.0, 0.0),) See http://trac.gispython.org/projects/PCL/wiki/PythonGeoInterface for more details on the interface. Testing ------- Several of the modules have docstring doctests:: $ cd shapely $ python point.py There are also two test runners under tests/. test_doctests.py requires zope.testing. runalldoctests.py does not. Perhaps the easiest way to run the tests is:: $ python setup.py test Support ------- For current information about this project, see the wiki_. .. _wiki: http://trac.gispython.org/projects/PCL/wiki/Shapely .. _manual: http://gispython.org/shapely/manual.html If you have questions, please consider joining our community list: http://trac.gispython.org/projects/PCL/wiki/CommunityList Credits ------- * Sean Gillies (Pleiades) * Howard Butler (Hobu, Inc.) * Kai Lautaportti (Hexagon IT) * Fr |eaigue| d |eaigue| ric Junod (Camptocamp SA) * Eric Lemoine (Camptocamp SA) * Justin Bronn (GeoDjango) for ctypes inspiration * Artem Pavlenko (Mapnik) for help with GEOS DLLs .. |eaigue| unicode:: U+00E9 :trim: Major portions of this work were supported by a grant (to Pleiades) from the U.S. National Endowment for the Humanities (http://www.neh.gov). Sean Gillies 6d4fc00ffb9c849f15b4c0b55833b29e33794116 1.0