Implement QgsGeometry.as_numpy and .as_shapely

[merydian]

Description

Adds methods to QgsGeometry to convert it to a (list of) numpy array(s) or shapely object(s). This is part of qgis/QGIS-Enhancement-Proposals#227. This enhancement improves integration with NumPy and Shapely while keeping them an optional dependency.

[github-actions]

🪟 Windows builds ready!

Windows builds of this PR are available for testing here. Debug symbols for this build are available here.

(Built from commit f60bf29)

[rouault]

shapely related things should be put in another try block, so that the raster part can work only if numpy is available

[roya0045]

What about geometries with Z/M coordinates?

[nyalldawson]

Does this work? It would save a copy of the data, and might squeeze out a bit more performance:

Suggested change

	shapely_geom = _shapely.from_wkb(wkb_bytes)
	shapely_geom = _shapely.from_wkb(wkb_qbytearray.data())

[github-actions]

The QGIS project highly values your contribution and would love to see this work merged! Unfortunately this PR has not had any activity in the last 14 days and is being automatically marked as "stale". If you think this pull request should be merged, please check

• that all unit tests are passing

• that all comments by reviewers have been addressed

• that there is enough information for reviewers, in particular

  • link to any issues which this pull request fixes

  • add a description of workflows which this pull request fixes

  • add screenshots if applicable

• that you have written unit tests where possible
  In case you should have any uncertainty, please leave a comment and we will be happy to help you proceed with this pull request.
  If there is no further activity on this pull request, it will be closed in a week.

[qgis-bot]

@merydian

This pull request has been tagged for the changelog.

• The description will be harvested so please provide a "nearly-ready" text for the final changelog
• If possible, add a nice illustration of the feature. Only the first one in the description will be harvested (GIF accepted as well)
• If you can, it's better to give credits to your sponsor, see below for different formats.

You can edit the description.

Format available for credits

• Funded by NAME
• Funded by URL
• Funded by NAME URL
• Sponsored by NAME
• Sponsored by URL
• Sponsored by NAME URL

Thank you!

[wonder-sk]

@merydian I am now getting a runtime error on QGIS start:

Couldn't load SIP module.  
Python support will be disabled.

Traceback (most recent call last):  
  File "", line 1, in  
  File "/home/martin/qgis/git-master/build/output/python/qgis/__init__.py", line 86, in  
    import qgis.gui  
  File "/home/martin/qgis/git-master/build/output/python/qgis/gui/__init__.py", line 26, in  
    from qgis.core import Qgis as _Qgis  
  File "/home/martin/qgis/git-master/build/output/python/qgis/core/__init__.py", line 22754, in  
    def _geometry_as_shapely(self) -> _shapely.geometry.base.BaseGeometry:  
AttributeError: module 'shapely' has no attribute 'geometry'

This is on ubuntu 22.04, shapely 1.8.0

I was able to fix this by doing:

import shapely.geometry as _sg

and then rewriting the offending line:

def _geometry_as_shapely(self) -> _sg.base.BaseGeometry:

Not sure why that does not work for me, and whether the fix is correct, but I assume others may get a similar issue...

[wonder-sk]

For the record, on ubuntu 24.04, shapely 2.0.3 things work fine without any modifications 🙂

[merydian]

Might this be a shapely issue?

There seem to be other people having similar issues. I think your fix is simple enough to just include? Tagging @nyalldawson for some input please.