[postgis-users] points to polyline or polygon

[Tyler Mitchell]

This is an interesting question to me.  If I understand correctly, you want
to "cast" a set of points into a linestring.  Getting your list of points
should be as easy as:

SELECT COLLECT(the_geom) FROM mytable GROUP BY somefield.

But this returns the geometry as MULTIPOINT, which isn't really want you
want, but if you see the text representation, it does look like a
linestring:

SRID=-1;MULTIPOINT(596681.75 5830977.5,532989.625 5869892,547653.0625
5808612,608081.1875 5799629)

So can anyone else give a pointer on taking the above output and casting it
into a linestring instead?

Tyler


                                                                                                                               
                      Randy James <rjames57 at yahoo.com>                                                                         
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                                                                Subject:  [postgis-users] points to polyline or polygon        
                                                                                                                               
                      07/15/2003 12:54 PM                                                                                      
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Hi

I managed to get a user interface with php mapscript that
inserts points in a postgis database, and now i am
attempting to insert lines and polygons from a web browser.
Has anyone done this?

I have a string of points that were entered in, one row per
point and was wondering if anyone has converted a string of
points to a line or polygon, or has a sample sql that will
do it.
I have a column in the table that has a ID for the line, I
am using the same ID on all points that I want merged into
a line. Than i hopefully can use a sql statement to select
all points with the same id and make them into a line, or
polygon.

Any input would be of help.

Cheers
Randy

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