[postgis-users] ST_Mapalgebra

[Joan]

Hi Tom,

Thanks for the help, the query now runs. There are no other quotes in the
query.

Regards

Joan

On 22 November 2011 15:16, Tom van Tilburg <tom.van.tilburg at gmail.com>wrote:

>  Joan,
>
> I think your expression is wrong.
> 'kb1.rast+kb.rast'
> should be:
> 'rast1+rast2'
>
> Oddly enough, I would not expect this error message with that error, so
> I'm curious wether it will make a change. Could it be there is any more
> quotes in the query that we can't see?
>
> Chrs,
>  Tom
>
>
> On 22-11-2011 14:24, Joan wrote:
>
> Hi Bborie,
>
>  I have used ST_MapAlgebraExpr but I get the error below.
>
>  select * from (select ST_MapAlgebraExpr(kb.rast, kb1.rast,
> 'kb1.rast+kb.rast') as rast from kb_dsm_clip kb, kb_dsm_clip100 kb1) as r1
> limit 5;
> ERROR: missing FROM-clause entry for table "kb1"
> LINE 1: SELECT (KB1.RAST+KB.RAST)::double precision
> ^
> QUERY: SELECT (KB1.RAST+KB.RAST)::double precision
>
>                                                              ^
>
>  At what point should I add :: double precision, I added it like this and
> also got an error.
>
>  select * from (select ST_MapAlgebraExpr(kb.rast, kb1.rast,
> 'kb1.rast+kb.rast')::double precision as rast from kb_dsm_clip kb,
> kb_dsm_clip100 kb1) as r1 limit 5;
> ERROR: cannot cast type raster to double precision
> LINE 1: ...AlgebraExpr(kb.rast, kb1.rast, 'kb1.rast+kb.rast')::double p...
> ^
>
>  Regards
>
>  Joan
>
>
>  On 21 November 2011 16:06, Bborie Park <bkpark at ucdavis.edu> wrote:
>
>>  On Mon, Nov 21, 2011 at 7:02 AM, Joan <wamaithajoan at gmail.com> wrote:
>> > Hello,
>> >
>> > When I run the following query
>> > select ST_MapAlgebra(r1.rast, r2.rast, "rast1 + rast2") from (select
>> > r1.rast, r2.rast from r1, r2) as foo limit 10;
>> > I get this error
>> > ERROR: column "rast + rast" does not exist
>> > LINE 1: ...t * from (select ST_MapAlgebra(r1.rast, r2.rast, "rast +
>> ra...
>> > ^
>> > What could be the problem? What is the correct syntax for st_mapalgebra?
>> > I have PostGIS installed the version updated on 18th Nov 2011.
>> >
>> > Joan
>>
>>  Hey Joan,
>>
>> You'll want to use ST_MapAlgebraExpr or ST_MapAlgebraFct.
>>
>>
>> http://postgis.refractions.net/documentation/manual-svn/RT_reference.html#Raster_Processing
>>
>> -bborie
>>
>> --
>> Bborie Park
>> Programmer
>> Center for Vectorborne Diseases
>> UC Davis
>> 530-752-8380
>> bkpark at ucdavis.edu
>> _______________________________________________
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>> postgis-users at postgis.refractions.net
>> http://postgis.refractions.net/mailman/listinfo/postgis-users
>>
>
>
>
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