https://github.com/pygeos/pygeos

Wraps GEOS geometry functions in numpy ufuncs.
https://github.com/pygeos/pygeos

Last synced: 3 months ago
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Wraps GEOS geometry functions in numpy ufuncs.

• Host: GitHub
• URL: https://github.com/pygeos/pygeos
• Owner: pygeos
• License: bsd-3-clause
• Created: 2019-06-10T11:03:57.000Z (over 5 years ago)
• Default Branch: master
• Last Pushed: 2022-12-14T19:31:24.000Z (almost 2 years ago)
• Last Synced: 2024-07-30T10:47:05.579Z (4 months ago)
• Language: Python
• Homepage: https://pygeos.readthedocs.io
• Size: 1.12 MB
• Stars: 374
• Watchers: 14
• Forks: 43
• Open Issues: 24
• Metadata Files:
  • Readme: README.rst
  • Changelog: CHANGELOG.rst
  • License: LICENSE

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README

        
======

PyGEOS

======

**Important note**: PyGEOS was merged with Shapely (https://shapely.readthedocs.io)

in December 2021 and has been released as part of Shapely 2.0. The development now takes place

at the Shapely repository. Please raise issues or create pull request over there.

PyGEOS itself will in principle not receive updates anymore.

.. Documentation at RTD — https://readthedocs.org

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PyGEOS is a C/Python library with vectorized geometry functions. The geometry

operations are done in the open-source geometry library GEOS. PyGEOS wraps

these operations in NumPy ufuncs providing a performance improvement when

operating on arrays of geometries.

What is a ufunc?

----------------

A universal function (or ufunc for short) is a function that operates on

n-dimensional arrays in an element-by-element fashion, supporting array

broadcasting. The for-loops that are involved are fully implemented in C

diminishing the overhead of the Python interpreter.

Multithreading

--------------

PyGEOS functions support multithreading. More specifically, the Global

Interpreter Lock (GIL) is released during function execution. Normally in Python, the

GIL prevents multiple threads from computing at the same time. PyGEOS functions

internally releases this constraint so that the heavy lifting done by GEOS can be

done in parallel, from a single Python process.

Examples

--------

Compare an grid of points with a polygon:

.. code:: python

  >>> geoms = points(*np.indices((4, 4)))

  >>> polygon = box(0, 0, 2, 2)

  >>> contains(polygon, geoms)

    array([[False, False, False, False],

           [False,  True, False, False],

           [False, False, False, False],

           [False, False, False, False]])

Compute the area of all possible intersections of two lists of polygons:

.. code:: python

  >>> from pygeos import box, area, intersection

  >>> polygons_x = box(range(5), 0, range(10, 15), 10)

  >>> polygons_y = box(0, range(5), 10, range(10, 15))

  >>> area(intersection(polygons_x[:, np.newaxis], polygons_y[np.newaxis, :]))

  array([[100.,  90.,  80.,  70.,  60.],

       [ 90.,  81.,  72.,  63.,  54.],

       [ 80.,  72.,  64.,  56.,  48.],

       [ 70.,  63.,  56.,  49.,  42.],

       [ 60.,  54.,  48.,  42.,  36.]])

See the documentation for more: https://pygeos.readthedocs.io

References

----------

- GEOS: https://libgeos.org

- Shapely: https://shapely.readthedocs.io/en/latest/

- Numpy ufuncs: https://docs.scipy.org/doc/numpy/reference/ufuncs.html

- Joris van den Bossche's blogpost: https://jorisvandenbossche.github.io/blog/2017/09/19/geopandas-cython/

- Matthew Rocklin's blogpost: http://matthewrocklin.com/blog/work/2017/09/21/accelerating-geopandas-1

Copyright & License

-------------------

PyGEOS is licensed under BSD 3-Clause license. Copyright (c) 2019, Casper van der Wel.

GEOS is available under the terms of ​GNU Lesser General Public License (LGPL) 2.1 at https://libgeos.org.