[postgis-users] PL/Python

[David Haynes]

Hello Remi,

Do you know who, what list I should report this to? In my work I found is
that plpython doesn't work well with the memory drivers for gdal or ogr.
Specifically when I would run the my code it might create the raster
dataset in memory and the for no apparent reason it would terminate the
database connection. I thought this was specific to gdal memory until I
encountered some downstream issues with vector datasets.

The error was resolved choosing actual directories and writing the data
there. I suppose that there would have to a specific plpython memory driver.



On Sat, May 21, 2016 at 5:04 AM, Rémi Cura <remi.cura at gmail.com> wrote:

> Hey,
> debuggin plpython is a bit of a pain.
> Maybe you are aware that you can use
> plpy.notice to print values during execution.
>
> This blog
> <http://geoexamples.blogspot.fr/2012/01/creating-files-in-ogr-and-gdal-with.html>
> seems to indicate that what you do should work:
>
> driver = gdal.GetDriverByName( 'MEM' )
> ds = driver.Create( '', 255, 255, 1, gdal.GDT_Int32)
>
>
> Maybe you can check that executing that in plain python while logged as postgres works?
>
> Cheers,
> Rémi-C
>
>
>
>
>
> 2016-05-18 21:26 GMT+02:00 David Haynes <haynesd2 at gmail.com>:
>
>> Yes because the second function in my doesn't error.
>>
>> On Wed, May 18, 2016 at 12:06 PM, Martijn Meijers <b.m.meijers at tudelft.nl
>> > wrote:
>>
>>> I think the gdal.getDriver call returns None. Hence the attribute error
>>> on the line afterwards. Are you sure that 19 is what you should pass as
>>> input?
>>>
>>> Martijn
>>>
>>> Verzonden vanaf mobiel.
>>>
>>>
>>> -------- Oorspronkelijk bericht --------
>>> Van: David Haynes
>>> Datum:18-05-2016 17:35 (GMT+01:00)
>>> Aan: postgis-users at lists.osgeo.org
>>> Onderwerp: [postgis-users] PL/Python
>>>
>>> Hello,
>>>
>>> I have a question regarding importing the gdal library using pl/python.
>>> Specifically, I want to create an in memory raster using the gdal library.
>>> This is a snippet of code that I have written,
>>>
>>> CREATE OR REPLACE FUNCTION terrapop_area_level_to_raster2(
>>> sample_geog_level_id bigint, raster_variable_id bigint, raster_band bigint)
>>> RETURNS text AS
>>> $BODY$
>>> from osgeo import gdal
>>> import numpy as np
>>> from osgeo import ogr, osr
>>>
>>> memDriver = gdal.GetDriver(19)
>>> #memDriver = gdal.GetDriverByName('MEM')
>>> memRast = memDriver.Create('', 10, 10, 1, gdal.GDT_Int32)
>>>
>>> This is the error I receive. A python NoneType error. Which seems to
>>> that the gdal class has not been imported. I have verified that gdal is
>>> available on the system.
>>>
>>> ERROR: AttributeError: 'NoneType' object has no attribute 'Create'
>>> SQL state: XX000
>>>
>>> However, this function on the same server and database returns to me all
>>> the gdal drivers. Any idea how I can diagnose this problem?
>>>
>>> CREATE OR REPLACE FUNCTION gdal_drivers()
>>>   RETURNS SETOF text AS
>>> $BODY$
>>>
>>> from osgeo import gdal
>>> driver = gdal.GetDriverByName('MEM')
>>> rast = driver.Create('', 2, 4, 1, gdal.GDT_Int32)
>>>
>>> names = []
>>> driverall = gdal.GetDriverCount()
>>> for i in range(gdal.GetDriverCount()):
>>> driver = gdal.GetDriver(i)
>>> drivername = driver.ShortName
>>> names.append([i,drivername])
>>>
>>> return names
>>>
>>> $BODY$
>>>   LANGUAGE plpythonu VOLATILE
>>>
>>>
>>>
>>>
>>>
>>>
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>>> postgis-users mailing list
>>> postgis-users at lists.osgeo.org
>>> http://lists.osgeo.org/mailman/listinfo/postgis-users
>>>
>>
>>
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