[postgis-users] linestring aggregation

[Nicolas Gillet - MARKET-IP]

Hello

 

I am trying to aggregate linestrings together based on their attributes and
the fact that they are touching each other.

 

Therefore I found out how to write a very basic aggregate function :

  

   CREATE AGGREGATE geometry_sum (

                SFUNC = st_union,

                BASETYPE = geometry,

                STYPE = geometry);

 

I can now aggregate my linestrings grouped by their names, importance, and
so on but . I have trouble to group them by the fact that they are touching
each other.

e.g.

linestring A, B and C have the same attributes but only A and B are touching
each other.

I would like as a result A+B in one record, and C in a second record.

 

Does someone have any tips to share ?

 

Thank you,

 

Nicolas

 

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