[OSGeo-Discuss] Command line tool for dissolving polygon boundaries

Dan Putler dan.putler at sauder.ubc.ca
Tue Mar 1 20:38:13 PST 2011

Hi Paolo, Simon, and Noli,

Thanks for this. It both answered my question as to whether there was an 
existing command line tool I had just overlooked (the answer is "no"), 
and what were my choices for something that could fairly easily be 
implemented if there wasn't an existing tool (the answer is "several"). 
At this point I'm going to look more deeply into several of these 

Thanks again,


On 03/01/2011 06:55 PM, Noli Sicad wrote:
> Hi Simon,
>> That sounds great.
>> I thought I remembered having read somewhere that Spatialite could
>> accept commands in this way but could not find a link to the webpage
>> when putting together my reply.
>> Can you provide a step by step outline of the code necessary to do this?
> It is in Spatialite Google Groups, here are the links.
> http://groups.google.com/group/spatialite-users/browse_thread/thread/7ecd6ccae76d3495/8683876813398de5?lnk=gst&q=Shapefile+#8683876813398de5
> ST_Union
> http://groups.google.com/group/spatialite-users/browse_thread/thread/2c8cc54d4b253979/78bc0b7eae6b1c38?lnk=gst&q=GUnion#78bc0b7eae6b1c38
>> Why is it necessary to create a CSV? Can't Spatialite manipulate
>> shapefiles directly in a virtual table?
> It is needed for matching e.g.
> ~~~~~~
> CREATE TABLE workplan AS SELECT * FROM property_mp JOIN planning
>         ON (property_mp.PR_PROPNUM = planning.PR_PROP_No);
> ~~~~~~
> where planning.PR_PROP_No is from CSV table.
> You can manipulate Shapefile as Virtual Shapefile. However,  you need
> a table for the criteria to be join and dissolve.
> It is easier to get the attribute table you need from the shapefile,
> if you like. Using MMQGIS plugin in QGIS you can export the attribute
> table into CSV file with ease.
> Noli
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