[postgis-users] RE: RE: Select Point or PolyGon Polyline in Box

Thu Apr 12 05:11:02 PDT 2007

To find the polygon where a point resides - there are actually several
ways of doing this and I'm not sure which one is fastest or the
preferred. There is (in these I am assuming the_poly is the polygon
geometry)

I usually just do the first because it is pretty all purpose for most of
the things I do and you don't have to think about the order of arguments
in distance like you have to in within)

SELECT * 
FROM polygon WHERE GeomFromText('POINT(295149 2315499)', -1) && the_poly
AND distance(the_poly, GeomFromText('POINT(295149 2315499)', -1)) = 0

There is also

SELECT * 
FROM polygon WHERE GeomFromText('POINT(295149 2315499)', -1) && the_poly
AND Within(GeomFromText('POINT(295149 2315499)', -1),the_poly)

For Poly Line's it's a little trickier because there is no such thing in
postgis lingo for Polyline.  I think the closest is Linestring or
MultiLineString. So if you have a linestring or multilinestring that
forms a polyline, I'm not sure if you would have to convert it to a
polygon using buildarea to get what you want or if you can get away with
some other relational operator to do it without conversion.  NOTE:  I
have never tried this before - this is simply a guess on my part

the_polyline is a linestring or multilinestring. 

SELECT * 
FROM polylines WHERE GeomFromText('POINT(295149 2315499)', -1) &&
the_polyline AND distance(BuildArea(the_polyline),
GeomFromText('POINT(295149 2315499)', -1)) = 0

OR

SELECT * 
FROM polylines WHERE GeomFromText('POINT(295149 2315499)', -1) &&
the_polyline AND Within(GeomFromText('POINT(295149 2315499)',
-1),BuildArea(the_polyline))

-----Original Message-----
From: postgis-users-bounces at postgis.refractions.net
[mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of
anhtin
Sent: Wednesday, April 11, 2007 11:40 PM
To: postgis-users at postgis.refractions.net
Subject: [postgis-users] RE: RE: Select Point or PolyGon Polyline in Box

Thanks very much  so support for me

if  i have that point i want select this point be in Polygon
ex: i have table Polygon is province.  i want select point(295054
849444) be
in Polygon  ????
and or be in polyline
can u show 2 way with polygon and polyline
thanks befor :)

Obe, Regina     DND\MIS wrote:
> 
> Don't quite get what you are asking?  Are you trying to compare if 2
> points are the same or if a point is within x distance of another
point?
> or something entirely different?
> 
> If you wanted to select all points within x distance of your reference
> point , then it would be (again replace -1 with the correct SRID and
> distance is always measured in the units of your spatial reference
> system)
> 
> SELECT * 
> FROM pointdemo
> WHERE the_point && Expand(GeomFromText('POINT(295149 2315499)', -1),
10)
> AND
> 	distance(the_point,GeomFromText('POINT(295149 2315499)', -1)) <=
> 10
> 
> If you wanted to know if 2 points are the same then it would be
> SELECT * 
> FROM pointdemo
> WHERE the_point ~= GeomFromText('POINT(295149 2315499)', -1)
>    
> 
>  
> 
> -----Original Message-----
> From: postgis-users-bounces at postgis.refractions.net
> [mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of
> anhtin
> Sent: Wednesday, April 11, 2007 12:32 AM
> To: postgis-users at postgis.refractions.net
> Subject: [postgis-users] RE: Select Point or PolyGon Polyline in Box
> 
> 
> thanks 
> How is Select if it is Point ?????
> 
> 
> 
> Obe, Regina     DND\MIS wrote:
>> 
>> Assuming your box is in the same srid as your points.  It would be
>> something like
>> 
>> SELECT *
>> FROM pointdemo
>> WHERE  the_point && setsrid('BOX(295149 2315499, 465992
>> 2163790)'::box2d, -1)
>> 
>> 
>> Note - above I am assuming your point geometry is called the_point
and
>> your SRID is -1
>> If the srid of your point geometry is not -1 then change  -1 to what
> it
>> should be.
>> 
>> 
>> -----Original Message-----
>> From: postgis-users-bounces at postgis.refractions.net
>> [mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of
>> anhtin
>> Sent: Tuesday, April 10, 2007 6:18 AM
>> To: postgis-users at postgis.refractions.net
>> Subject: [postgis-users] Select Point or PolyGon Polyline in Box
>> 
>> 
>> hi all
>> i have question to postgis
>> i have table Pointdemo
>> I want select all point in my Box("Rectangle") on PostGis
>> my box is corrdinate 
>> ex: full extend is:Box(110638 2587481, 903350 1972446) ---> xmin
ymin,
>> xmax
>> ymax
>> i want select point in Box(295149 2315499, 465992 2163790)  ---> xmin
>> ymin,
>> xmax ymax
>> How will i do that ?????
>> 
>> 
>> -- 
>> View this message in context:
>>
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>> 
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> 
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