petern48 commented on code in PR #2772:
URL: https://github.com/apache/sedona/pull/2772#discussion_r2969876271
##########
python/sedona/spark/geopandas/base.py:
##########
@@ -489,9 +489,36 @@ def is_ring(self):
"""
return _delegate_to_geometry_column("is_ring", self)
- # @property
- # def is_ccw(self):
- # raise NotImplementedError("This method is not implemented yet.")
+ @property
+ def is_ccw(self):
+ """Return True for Polygon/MultiPolygon geometries whose exterior ring
+ is counter-clockwise oriented.
+
+ Returns False for non-polygon geometry types (e.g. LineString, Point).
+
+ Notes
+ -----
+ Unlike geopandas, which also supports LinearRing inputs, this
+ implementation uses Sedona's ``ST_IsPolygonCCW`` which only recognises
+ Polygon and MultiPolygon geometries. All other geometry types return
+ ``False``.
Review Comment:
We actually had a previous contribution attempt for `is_ccw()`, and
encountered this problem, and we agreed not to implement it for now
(https://github.com/apache/sedona/pull/2386#discussion_r2422383890), given it's
not easy to replicate the full desired behavior. We're not just missing proper
behavior for LinearRings (which are rare), but we would have the incorrect
behavior for `LineString`s, which are very common. As you can see in the code
snippet below, `LineString` can evaluate to True here too, but our existing
`ST_IsPolygonCCW()` isn't capable of determining that at the moment.
```python
import shapely
from shapely import LineString
from geopandas import GeoSeries
ls = LineString([[0, 0], [1, 0], [1, 1], [2, 2]])
gs = GeoSeries(ls)
print(gs.is_ccw)
```
In order to implement proper support for `is_ccw()`, I think we would need
to investigate doing some more changes in the actual Java code and potentially
look into the upstream JTS library. Given that complexity, I would rather skip
implementing it entirely for now (or at least in a separate PR if you really
want to investigate it, though it would be harder). Could we remove it for now?
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