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Prepared contains differs from normal contains

See original GitHub issue

This fails. I don’t think it should. I could be mistaken though.

from shapely.geometry import Point, Polygon
import shapely.prepared

point = Point(0.95, 0.05)
geom = Polygon([(0, 0), (1, 0), (0, 1), (0, 0)])

assert shapely.prepared.prep(geom).contains(point) == geom.contains(point)

>>> shapely.__version__
'1.6b4'

I’m on linux. I’ve installed Shapely from conda-forge.

Issue Analytics

State:
Created 6 years ago
Comments:12 (7 by maintainers)

Top GitHub Comments

2reactions

sgilliescommented, Sep 6, 2017

This seems to be a wontfix and I’ve closed the upstream issue. Strictly speaking, the point is on the boundary of the polygon and thus is not contained. Due to numerical precision issues, it may be computed to not be on the boundary, and that’s what I see in my test. Something has changed since 3.4.2, but the results are actually more correct for one of the polygons. I didn’t note above whether it was prep(geom).contains(point) or geom.contains(point) that was False with GEOS 3.5.1.

1reaction

sgilliescommented, Sep 6, 2017

I’ve created a ticket upstream: https://trac.osgeo.org/geos/ticket/841. @mrocklin @snorfalorpagus can you confirm that I reported correctly?

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