[postgis-devel] Is there a reason those GArray functions aren't documented?

Obe, Regina robe.dnd at cityofboston.gov
Tue Jul 1 03:48:46 PDT 2008

I was assuming it is because we consider them internal like functions
since they are used to form the aggregate functions and may be something
that changes in the future.  

I finally found a use for them somewhat directly and felt a little dirty
using them.

Case in point.  Someone asked me how to formulate a polygon if he has a
known finite set of points he pulled out of a hat (well a hat that forms
points forming a closed ring - not coming from an aggregate rollup)

After looking thru the docs and the closest thing I could come up with
using documented
functions was


which would require me to get my points into a multipoint (using yet
another undocumented GArray function or using a messy union all).

I then found all these undocumented garray functions used to form the
aggregates which allowed me to write a function using ST_MakeLineGArray.

CREATE OR REPLACE FUNCTION upgis_makepolygonfrompoints(points
  RETURNS geometry AS
	SELECT ST_MakePolygon(ST_MakeLine_GArray($1))


COMMENT ON FUNCTION upgis_makepolygonfrompoints(geometry[]) IS 'Takes an
array of points and returns a polygon formed from those points.  
upgis_makepolygonfrompoints(ARRAY[ST_MakePoint(1,1), ST_MakePoint(2,1),
ST_MakePoint(2,0), ST_MakePoint(1,0), ST_MakePoint(1,1)]) ';

Which allows me to do something perverse like this

SELECT upgis_makepolygonfrompoints(ARRAY[ST_MakePoint(1,1),
ST_MakePoint(2,1), ST_MakePoint(2,0), ST_MakePoint(1,0),


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