ENH: vectorized function to force orientation of polygon rings

[jorisvandenbossche]

Similar as pygeos/pygeos#71

Shapely has a custom function to force the orientation of a geometry: shapely.ops.orient (impl. But, this is currently a pure python function. Because this is not something that is supported by GEOS out of the box, this is also not supported by a vectorized ufunc that were merged from pygeos.

It would be good to add a vectorized ufunc version of orient.

As reference, PostGIS has ST_ForcePolygonCCW and related functions.

[dr-jts]

Feel free to file a GEOS issue to request this. Perhaps a function GEOSOrientPolygon(Geometry, boolean isCW), to allow orienting either shell-CW (the GEOS default) or shell-CCW.

Note that GEOSNormalize doesn't really provide all this, since (a) it always orients shell-CW (which seems to be not what is wanted nowadays) and (b) it can rotate rings (which is a bigger change than just reorienting them).

[idanmiara]

Until a more optimized solution is proposed (ufunc, geos, etc...):
#1690 could be an alternative solution.

[jorisvandenbossche]

Opened libgeos/geos#779 to track this upstream in GEOS

[idanmiara]

Please see new implementation for force_ccw in #1690