On Mar 10, 2010, at 9:59 AM, Oliver Christen wrote:
hello
I have a problem loading with shapely a geometry returned by a query
in postgis.
the system I use return the geometry as it is stored in postgis,
something like this:
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
I have found on the web an example of loading such string in shapely
using:
from shapely.wkb import loads
geo=loads(data.decode('hex'))
but this only result in the error:
shapely.geos.ReadingError: Could not create geometry because of
errors while
reading input.
loads should receive a wkb and data.decode('hex') does not seem to
produce a valid wkb
data.decode('hex') produce something like this:
\x01\x06\x00\x00\xe0\x15U
\x00\x00\x01\x00\x00\x00\x01\x03\x00\x00\xc0\x01\x00\x00\x00\x08\x00\x00\x00\x01\x8a\x91\xd5\x17\xd9\x1eA\x01n\x16\xef\xcbB\x01A\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff\xff\xff\xff\xff\xef\xff\xb2\xd8&\x85\xba\xd9\x1eA;\x8b\xde\xa9\xbeA\x01A\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff\xff\xff\xff\xff\xef\xff\x19rl}r\xd9\x1eA\x02)\xb1\x0b\rA\x01A\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff\xff\xff\xff\xff\xef\xff\x8bQ\xd7z/\xd9\x1eAL\xa8\xe00\x8dA\x01A\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff\xff\xff\xff\xff\xef\xff\xc4]\xbd\xba\xfb\xd8\x1eA\xb8<\xd6\x0c\xfaA\x01A\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff\xff\xff\xff\xff\xef\xff\\r\xdc\xe9\xef\xd8\x1eAkdWz5B\x01A\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff\xff\xff\xff\xff\xef\xff\xbbB\x1f\x0c\xfa\xd8\x1eA\xb7\xb4\x1a\x92\x91B\x01A\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff\xff\xff\xff\xff\xef\xff\x01\x8a\x91\xd5\x17\xd9\x1eA\x01n\x16\xef\xcbB\x01A\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff\xff\xff\xff\xff\xef\xff
but if I use ST_AsBinary(the_geom) in postgres to generate a wkb, I
get something like this:
001\006\000\000\000\001\000\000\000\001\003\000\000\000\001\000\000\000\010\000\000\000\001\212\221\325\027\331\036A\001n\026\357\313B\001A\262\330&\205\272\331\036A;\213\336\251\276A\001A\031rl}r\331\036A\002)\261\013\015A\001A\213Q\327z/\331\036AL\250\3400\215A\001A\304]\275\272\373\330\036A\270<\326\014\372A\001A\\r\334\351\357\330\036AkdWz5B\001A\273B\037\014\372\330\036A\267\264\032\222\221B\001A\001\212\221\325\027\331\036A\001n\026\357\313B\001A
if I try to load that string with loads in shapely.wkb, it works
perfectly and the geometry is correct
decode('hex') doesnt not seem to be the correct way to convert
postgis geom string into wkb,
so what python command should I use to produce a valid wtb from the
postgis geom string ?
thanks in advance
best regards
Oliver
What version of PostGIS are you using? The latest? Did the project
change the format in which it stores geometries? If so, ST_AsBinary is
what you'll want to use now.
Cheers,
--
Sean
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