WKBWriter produces invalid WKB data

[snorfalorpagus]

The wkb and wkb_hex methods are giving me the wrong output (see code sample below). I'm not sure if this is an issue with shapely, or the underlying GEOS library (which I compiled myself).

>>> from shapely.geometry import Point
>>> from shapely.wkb import loads
>>> p = Point(2.0, 4.0)
>>> p.wkt
'POINT (2 4)'
>>> p.wkb_hex
'010100000000000000000000000000000000000000'
>>> p2 = loads(p.wkb_hex, hex=True)
>>> p.x, p.y
(2.0, 4.0)
>>> p2.x, p2.y
(2.722673383505394e-306, 2.722673383505394e-306)

I'm running Python 2.7.6 (32 bit) on Windows 7 with GEOS 3.4.2 (compiled with MinGW32).

[mwtoews]

Yup, that's doing something weird. Did your build of GEOS pass the tests? (make check). Do you have multiple copies of GEOS libraries?

I left some of the older readers and writers in place, which raise a DeprecationWarning. Try p.to_wkb().encode('hex') (the others writer is p.to_wkt())

Furthermore, the old readers are:

from shapely.geometry import base
base.geom_from_wkt('POINT(2 4)').to_wkt()
base.geom_from_wkb('010100000000000000000000400000000000001040'.decode('hex')).to_wkt()

[snorfalorpagus]

This does indeed seem to be a problem with my GEOS build. The tests fail, and it looks like the errors are related to similarly empty geometries. I'll follow this up on the GEOS mailing list, but I guess this issue can be closed.

The shapely test cases do seem to catch this as well:

======================================================================
FAIL: test_polygon (shapely.tests.test_polygon.PolygonTestCase)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "d:\Shapely\shapely\tests\test_polygon.py", line 64, in test_polygon
    self.assertEqual(ring.coords[0], (0., 0.))
AssertionError: Tuples differ: (7.994349224597053e-307, 7.994... != (0.0, 0.0)

First differing element 0:
7.9943492246e-307
0.0

- (7.994349224597053e-307, 7.994349224597053e-307)
+ (0.0, 0.0)

Serves me right for not running the tests when installing things...