[postgis-devel] EMPTY

[Paul Ramsey]

No, I don't think so... disjoint == true, and if you think of empty as
being the absence of something, they are all exterior...

FFF
FFF
FF2

On Tue, Oct 6, 2009 at 2:21 PM, Paul Ramsey <pramsey at cleverelephant.ca> wrote:
> Meaning FFFFFFFFF ? :)
>
> On Tue, Oct 6, 2009 at 2:25 PM, Martin Davis <mbdavis at refractions.net> wrote:
>> FALSE!!!!
>>
>> Paul Ramsey wrote:
>>>
>>> OK, the uber question (Kevin can meditate over this one tonight):
>>>
>>> ST_Relate(geometry, empty)
>>> ST_Relate(empty, empty)
>>>
>>>  :)
>>>
>>> On Tue, Oct 6, 2009 at 2:11 PM, Paragon Corporation <lr at pcorp.us> wrote:
>>>
>>>>
>>>> Yap 0 on all counts.  Wow those Microsoft people are really smart.
>>>>
>>>>  --geometry contains empty
>>>>  SELECT Geometry::STGeomFromText('POINT(1
>>>> 2)',4326).STContains(Geometry::STGeomFromText('POLYGON EMPTY',4326))
>>>>       => 0
>>>>
>>>> --geometry within empty
>>>>  SELECT Geometry::STGeomFromText('POINT(1
>>>> 2)',4326).STWithin(Geometry::STGeomFromText('POLYGON EMPTY',4326))
>>>>        => 0
>>>>
>>>> --empty contains geometry
>>>>  SELECT Geometry::STGeomFromText('POLYGON
>>>> EMPTY',4326).STContains(Geometry::STGeomFromText('POINT(1 2)',4326))
>>>>  => 0
>>>>
>>>>  --empty within geometry
>>>> SELECT Geometry::STGeomFromText('POLYGON
>>>> EMPTY',4326).STWithin(Geometry::STGeomFromText('POINT(1 2)',4326))
>>>>  => 0
>>>>
>>>> Thanks,
>>>> Regina
>>>>
>>>> -----Original Message-----
>>>> From: postgis-devel-bounces at postgis.refractions.net
>>>> [mailto:postgis-devel-bounces at postgis.refractions.net] On Behalf Of Chris
>>>> Hodgson
>>>> Sent: Tuesday, October 06, 2009 5:03 PM
>>>> To: PostGIS Development Discussion
>>>> Subject: Re: [postgis-devel] EMPTY
>>>>
>>>> I agree with you Regina, and I bet SQL Server does too.
>>>>
>>>> Chris
>>>>
>>>> Paragon Corporation wrote:
>>>>
>>>>>
>>>>> They should all be false.
>>>>>
>>>>> Isn't the first requirement of containment/contains be that the two
>>>>> geometries intersect -- so if we say empty can't intersect with
>>>>> anything including empty, how can anything possibly contain  it?
>>>>>
>>>>> Though have to pull out my sql server 2008 to see if it is in agreement.
>>>>>
>>>>> Thanks,
>>>>> Regina
>>>>>
>>>>>
>>>>>
>>>>> -----Original Message-----
>>>>> From: postgis-devel-bounces at postgis.refractions.net
>>>>> [mailto:postgis-devel-bounces at postgis.refractions.net] On Behalf Of
>>>>> Paul Ramsey
>>>>> Sent: Tuesday, October 06, 2009 4:39 PM
>>>>> To: PostGIS Development Discussion
>>>>> Subject: Re: [postgis-devel] EMPTY
>>>>>
>>>>> In the spirit of maintaining the geometry logical flow, what do you
>>>>> think of these ideas?
>>>>>
>>>>>  * ST_Contains(geometry, empty) == TRUE
>>>>>  * ST_Within(geometry, empty) == FALSE
>>>>>  * ST_Contains(empty, geometry) == FALSE
>>>>>  * ST_Within(empty, geometry) == TRUE
>>>>>
>>>>> What does SQL Server say?
>>>>>
>>>>> P
>>>>>
>>>>> On Tue, Oct 6, 2009 at 1:34 PM, Paul Ramsey
>>>>> <pramsey at cleverelephant.ca>
>>>>> wrote:
>>>>>
>>>>>
>>>>>>
>>>>>> I'm going to change my intersection/disjoint answers to agree w/ SQL
>>>>>> Server. They are not bad, and they maintain the symmetry between
>>>>>> where intersection => ! disjoint.
>>>>>>
>>>>>> P.
>>>>>>
>>>>>> On Tue, Oct 6, 2009 at 12:45 PM, Chris Hodgson
>>>>>> <chodgson at refractions.net>
>>>>>>
>>>>>>
>>>>>
>>>>> wrote:
>>>>>
>>>>>
>>>>>>>
>>>>>>> I moved these and summarized the interesting results from SQL Server
>>>>>>> 2008 next to your original lines Paul.
>>>>>>>
>>>>>>> Note that SQL Server says that everything is disjoint from empty,
>>>>>>> including empty itself - whereas your original guesses were to
>>>>>>> return
>>>>>>>
>>>>>>>
>>>>>
>>>>> false.
>>>>>
>>>>>
>>>>>>>
>>>>>>> So far I think I like SQL Server's answers. Would be good to compare
>>>>>>> with oracle spatial too.
>>>>>>>
>>>>>>> Chris
>>>>>>>
>>>>>>> Paul Ramsey wrote:
>>>>>>>
>>>>>>>
>>>>>>>>
>>>>>>>> Regina, could you move your SQL Server examples down to a big block
>>>>>>>> at the end, so the main part of the document is more readable? So
>>>>>>>> far I agree with SQL Server in all the examples! Those guys are
>>>>>>>> smart! :)
>>>>>>>>
>>>>>>>> P
>>>>>>>>
>>>>>>>> On Tue, Oct 6, 2009 at 12:12 PM, Paul Ramsey
>>>>>>>> <pramsey at cleverelephant.ca>
>>>>>>>> wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>>
>>>>>>>>> On Tue, Oct 6, 2009 at 12:03 PM, Chris Hodgson
>>>>>>>>> <chodgson at refractions.net>
>>>>>>>>> wrote:
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> I would dare say that geometry empty is more like zero, than null.
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Bingo, there's a useful mental model. Wikify that!
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>
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>>>>>>>>
>>>>>>>>
>>>>>>>
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>>>>>>>
>>>>>
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>>
>> --
>> Martin Davis
>> Senior Technical Architect
>> Refractions Research, Inc.
>> (250) 383-3022
>>
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