[postgis-users] Possible function to convert +-180featuresto0-360 longitudes

[Obe, Regina]

Stan,
 
I know I look like a command line glutton, but I use PgAdmin III a lot and actually that's how I read the comments.
 
In the right hand pane on the properties pane at the very bottom is a field that displays the comments.  That's what got me thinking - shame PostGIS functions have no comments - now I've got to leave my screen to go find the definition in the manual which tells me a convex hull is a convex hull.  
 
I was wondering about the arcane not referencing variables by there names in the args list.  That was another thing that drives me a tad bit nuts, so I'm glad you mentioned it.
 
Paul,
 
Does this mean also that we definition committers can come up with more meaningful comments that a lay user has a chance of understanding - instead of 
 
ST_ConvexHull -- Return the convex hull of the ST_Geometry value.
 
Sorry for nit-picking.  I know REAL GIS users already know what a convex hull is.
 
Thanks,
Regina
 
 

________________________________

From: postgis-users-bounces at postgis.refractions.net on behalf of Sufficool, Stanley
Sent: Fri 6/20/2008 11:31 AM
To: PostGIS Users Discussion
Subject: RE: [postgis-users] Possible function to convert +-180featuresto0-360 longitudes



Is there a way to get the comments to show in pgAdmin when clicking
through the functions? This would be OH SO helpful.

I'm forced to use SQL Server 2005 daily, but the one thing I see SQL
having is NAMED arguments to procedures and functions. I know PG deals
with this differently. However, if the code/comments could provide a
clue as to the arguments that a function receives and produces, this
would be very helpful.

> -----Original Message-----
> From: postgis-users-bounces at postgis.refractions.net
> [mailto:postgis-users-bounces at postgis.refractions.net] On
> Behalf Of Obe, Regina
> Sent: Friday, June 20, 2008 5:25 AM
> To: PostGIS Users Discussion
> Subject: RE: [postgis-users] Possible function to convert
> +-180 featuresto0-360 longitudes
>
>
> Paul,
>
> I don't see this function defined in the docs.  Am I missing
> where it is.
>
> Also I was thinking - would be nice if when we built all
> these functions we put comments as to what they do in the
> comments metadata section of postgres.  It would have 2
> positive effects
>
> 1) When I'm scanning thru the functions in my database as I
> normally do
> - I would know what it does and probably how to use it
> without having to refer to the manual
>
> 2)
> I imagine it would also make auto-generation of documentation
> a bit easier too.  Example
>
> CREATE OR REPLACE FUNCTION st_shift_longitude(geometry)
>   RETURNS geometry AS
> '$libdir/liblwgeom', 'LWGEOM_longitude_shift'
>   LANGUAGE 'c' IMMUTABLE STRICT;
> COMMENT ON FUNCTION st_shift_longitude(geometry) IS 'Reads
> every point/vertex in every component of every feature in a
> geometry, and if the longitude coordinate is <0, adds 360 to
> it. The result would be a 0-360 version of the data to be
> plotted in a 180 centric map';
>
>
> Just my two cents,
> Regina
>
>
> -----Original Message-----
> From: postgis-users-bounces at postgis.refractions.net
> [mailto:postgis-users-bounces at postgis.refractions.net] On
> Behalf Of Paul Ramsey
> Sent: Friday, June 20, 2008 2:47 AM
> To: pcreso at pcreso.com; PostGIS Users Discussion
> Subject: Re: [postgis-users] Possible function to convert
> +-180 features to0-360 longitudes
>
> ST_Shift_Longitude?
>
> On Fri, Jun 20, 2008 at 5:52 AM,  <pcreso at pcreso.com> wrote:
> > Hi,
> >
> > I believe such a function is feasible, but my programming skills are
> pretty minimal, so any advice appreciated.
> >
> > I have data in a custom mercator projection, crossing 180 degrees. I
> can use ST_transform to generate a lat/long (EPSG:4326)
> version, but only in a +-180 longtitudinal space, which
> results in features at each side of a map with lines joining
> them running across the map.
> >
> > It seems feasible to have a function (to360 ?) which reads every
> point/vertex in every component of every feature in a
> geometry column, & if the longitude coordinate is <0, adds
> 360 to it. The result would be a 0-360 version of the data to
> be plotted in a 180 centric map.
> >
> > Given the original data was not split at 180, this should simply
> rebuild the correct topology of the features. I'm not looking
> to split or join features which cross the 180 or 0 longitude lines.
> >
> > So, am I wrong in any of my assumptions, & if not, can
> anyone point me
> to some relevant examples to learn from or suggest how I
> should go about writing such a function?
> >
> >
> > Thanks,
> >
> >   Brent Wood
> > _______________________________________________
> > postgis-users mailing list postgis-users at postgis.refractions.net
> > http://postgis.refractions.net/mailman/listinfo/postgis-users
> >
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