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devel / comp.lang.python / Shapely Polygon creating empty polygon

Shapely Polygon creating empty polygon

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From: ijbrewster@alaska.edu (Israel Brewster)
Newsgroups: comp.lang.python
Subject: Shapely Polygon creating empty polygon
Date: Tue, 4 Jan 2022 13:57:26 -0900
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by: Israel Brewster - Tue, 4 Jan 2022 22:57 UTC

I’m running into an issue with shapely that is baffling me. Perhaps someone here can help out?

When running shapely directly from a python 3.8 interpreter, it works as expected:

>>> import shapely
>>> shapely.__version__
'1.8.0'
>>> from shapely.geometry import Polygon
>>> bounds = [-164.29635821669632, 54.64251856269729, -163.7631779798799, 54.845450778742546]
>>> print(Polygon.from_bounds(*bounds))
POLYGON ((-164.2963582166963 54.64251856269729, -164.2963582166963 54.84545077874255, -163.7631779798799 54.84545077874255, -163.7631779798799 54.64251856269729, -164.2963582166963 54.64251856269729))

However, if I put this exact same code into my Flask app (currently running under the Flask development environment) as part of handling a request, I get an empty polygon:

>>> import shapely
>>> print(shapely.__version__)
>>> from shapely.geometry import Polygon
>>> print(Polygon.from_bounds(*bounds))

Output:

1.8.0
POLYGON EMPTY

In fact, *any* attempt to create a polygon gives the same result:
>>> test = Polygon(((1, 1), (2, 1), (2, 2)))
>>> print(test)
POLYGON EMPTY

What am I missing here? Why doesn’t it work as part of a Flask request call?
---
Israel Brewster
Software Engineer
Alaska Volcano Observatory
Geophysical Institute - UAF
2156 Koyukuk Drive
Fairbanks AK 99775-7320
Work: 907-474-5172
cell: 907-328-9145

Subject	Author
Shapely Polygon creating empty polygon	Israel Brewster