[postgis-users] Why unrecognized field type?

[Lee Hachadoorian]

On Tue, Dec 3, 2013 at 11:50 AM, James David Smith <
james.david.smith at gmail.com> wrote:

> On 3 December 2013 15:55, Lee Hachadoorian <Lee.Hachadoorian+L at gmail.com>wrote:
>
>> On Tue, Dec 3, 2013 at 5:23 AM, James David Smith <
>> james.david.smith at gmail.com> wrote:
>>
>>> Hi all,
>>>
>>> Apologies for cross-posting this to the RPostrgeSQL and PostGIS mailing
>>> lists, but I'm not sure where the problem lies.
>>>
>>> I am using the RPostgreSQL package of R to connect to my installation of
>>> PostgreSQL/PostGIS. I want to retrieve some coordinates from my database
>>> and run the below command. Is this just that R doesn't know what to do with
>>> Geometry's, or is it something I should be more concerned about? I ask, as
>>> I'm having some wider issues with my workflow and this may be related.
>>>
>>> Thanks
>>>
>>> James
>>>
>>> > dbGetQuery(con, "SELECT st_transform(st_setsrid(st_makepoint(soose::numeric, soosn::numeric),27700),4326) FROM stage WHERE ssid = '707187161010202'")
>>>
>>> st_transform
>>> 1 0101000020E6100000F71184EF3961B3BF830420AF33C64940Warning message:In postgresqlExecStatement(conn, statement, ...) :
>>>   RS-DBI driver warning: (unrecognized PostgreSQL field type geometry (id:480912) in column 0)
>>>
>>>
>>>
>> James,
>>
>> R knows how to handle geometries using the sp package, but can't read the
>> data in using RPostgreSQL. You would need to use readOGR() in the rgdal
>> package. But what data do you actually need in R, and what do you intend to
>> do with it? If you're not going to be mapping it or doing spatial
>> statistics on it, there may be a way to get the data you want using
>> RPostgreSQL.
>>
>> Best,
>> --Lee
>>
>
> Hi Lee,
>
> Thanks for the reply.  I was really only after the x and y of the geom, so
> I'm now using st_x and st_y functions to get that. I've also figured out
> what was going on with my wider workflow (a typo!) , so now all is working
> fine. It was good to understand how R deals with geom types though for
> future reference.
>
> Cheers
>
> James
>
>
That's what I suspected, so I was going to suggest what you've already
figured out. BTW, R + PostGIS is an excellent toolchain, so if you do
decide to push in that direction, Advanced Spatial Data Analysis with R by
Bivand, et al. will be indespendible.

http://www.asdar-book.org/

Best,
--Lee
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