[Cubicweb] Postgis and Shapely

[Rémi Cardona]

Hi Christophe,

Le 01/01/2014 11:47, Christophe de Vienne a écrit :
> Going through geoalchemy-2 [1] documentation, I discovered it is
> integrated with Shapely [2], which is itself based on the same engine
> postgis use (geos).
> So I wondered if someone already had a look to Shapely and if it could
> be integrated with the postgis cube ?

When working on the postgis cube a few months ago, I did stumble upon 
Shapely and its sibling Fiona and started using them.

Overall, I was quite pleased with the Shapely/Fiona combo. Especially 
when compared against the official geos/GDAL python bindings. Those are 
needlessly complex to use and incredibly fragile, I gave up on them 
after the second NULL-pointer dereference I got when toying with them in 
IPython.

Going back to Shapely, I ended up not using it in the postgis cube for 2 
reasons:

* lack of clean RPM packages. Not Shapely's fault, but it did hamper its 
use for our first production deployment.
* no indexing facility to help with large intersection computations 
(again, a feature needed for the aforementioned deployment)

The bottom line was that PostGIS was doing a much better job with all 
the gigabytes of GIS data we fed it and the need for Shapely pretty much 
disappeared.

As for proper CubicWeb support, this would require some more work in 
yams, logilab-database and cubicweb proper. Not an easy task (basically 
a comprehensive "public" API for cube-defined final types), but a 
worthwhile one IMHO.

Cheers :)

-- 
Rémi Cardona - LOGILAB, Paris (France).
Tél: 01.45.32.03.12
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