[postgis-users] Retrieve Line coordinates from geometry.

[Rodrigo Martín LÓPEZ GREGORIO]

Hi Broun.

If you want the start point of a linestring then you must use:

StartPoint(the_geom)

This function returns a POINT with the coordinates of the start point from
the_geom (for the end point you should use EndPoint(the_geom))

If you want to get the X and Y coordinates you should use the X() and Y()
functions with that points like:

X(StartPoint(the_geom)) and Y(StartPoint(the_geom))

Rodrigo.

On 7/5/07, Broun Uganda <tekuganda at hotmail.com> wrote:
>
> Dear all,
> Am trying to use the postgis reference to extract coordinates (x & y) for
> the starting and ending of a line from the_geom to enable me draw points
> at the starting and ending of that line. Please advise me which function i
> should use in my trigger function.
> I want to do something like this:
> UPDATE points SET the_geom = MakePoint(New.lines.the_geom(s),-1); where
> (s) refers to start of line geometry & (e) refers to end  of line geometry
> UPDATE points SET the_geom = MakePoint(New.lines.the_geom(e),-1);
>
>
> Thanks
>
> Broun
>
>
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