[Community] Shapely is_empty fails on Linux

[Sean Gillies]

On Jan 21, 2010, at 5:35 PM, Patrick Hartling wrote:

> Howard Butler wrote:
>> On Jan 21, 2010, at 9:30 AM, Patrick Hartling wrote:
>>
>>> We have run into a strange problem with the is_empty property on  
>>> Shapely
>>> goemetry objects failing on Linux. We are using r1485 from the  
>>> Shapely 1.2
>>> branch with GEOS 3.1.1 and Python 2.6.2 on 64-bit Ubuntu Linux  
>>> 9.04. The
>>> code below demonstrates the problem:
>>>
>>> import shapely.geometry
>>> assert shapely.geometry.Point(1,1).is_empty == False
>>
>> What about this?  Maybe the chaining is causing the reference to go  
>> bad.
>>
>> p = shapely.geometry.Point(1,1)
>> p.is_empty
>
> The result is the same in that case: is_empty still returns False.
>
> -Patrick

An "empty" geometry is an odd beast. Not quite the same as None, it's  
a reflection of whether the geometry has coordinates or a sequence of  
coordinates. A Point with x and y values set is definitely not empty.  
The following is correct:

   >>> from shapely.geometry import Point
   >>> p = Point(0, 0)
   >>> p.is_empty
   False

Thanks for trying the code, Patrick. I'm going to try to make a second  
alpha release of 1.2 tonight or tomorrow and will notify this list.

Cheers,

--
Sean