[QGIS-Developer] Intersections with Qgis

[Bo Victor Thomsen]

Johannes -

The actual intersection code can contain a pre-check of bounding box 
intersection. This will probably  decrease computation time 
significantly for the check:

for i, geom_i in enumerate(geoms):
     for j, geom_j in enumerate(geoms):
         if j > i:

             # Check bounding box first...
             result = geom_i.boundingBoxIntersects(geom_j)

             if result:

                 # Bounding box intersects, check actual geometry...
                 result = geom_i.intersects(geom_j)

             # Do something with result...


-- 
Med venlig hilsen / Kind regards

Bo Victor Thomsen


Den 06-04-2020 kl. 11:36 skrev Johannes Wildermuth:
> Hello developers
> I've been currently working on a python plugin in which I have to find 
> all possible intersections on one layer. I want to improve the 
> efficiency of this task. It roughly looks like this:
> for i, geom in enumerate(geoms):
>     for j, geom in enumerate(geoms):
>         if j > i:
>             //intersections
> Is there a faster way? Perhaps with multithreading / rtree?
> Regards
> Johannes Wildermuth
>
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