[postgis-users] Call for Semantics (ST_CollectionTypes())

Paul Ramsey pramsey at opengeo.org
Wed Jan 28 12:52:47 PST 2009

I would like to add a function that takes an anonymous
GEOMETRYCOLLECTION and returns something more structured:
- a GEOMETRYCOLLECTION where the first element is a MULTLIPOLYGON, the
second a MULTILINESTRING and the third a MULTIPOINT?
- a tuple, with elements 'polygons', 'linestrings', 'points', each
with one multi* of each?
- a tuple, with elements 'polygons', 'linestrings', 'point', each with
an array of singletons?

The key here is to provide a useful flat structure to pull info out
of. Some information in the GEOMETRYCOLLECTION *will be lost*, (but
that seems an acceptable price)

Another approach, which might be simpler for users to grok would be:

ST_CollectionAsMultiPolygon() returns just the polygon elements of a collection.
... etc ...



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