[BUGS] Bug? (geo operator @ )

[Daniel Lau]

Hi all,

I was to extract the '_lines' (path) if the lines are contained or on by a
box-like polygon. The result turns wrong if the box-like polygon is
changed from a square (x_max = y_max) to a rectangle (x_max <> y_max).
Please read the example at the end.

Please also notice that although the _lines #2 is contained by both square
and rectangle, it does not appear in both table. 

I am wondering if it is a bug. Perhapes I did something wrong?

regards,
Daniel Lau
Hong Kong University of Science and Technology


Example:
_

test=# select * from test;
 geoid |_lines
---+---
 0 | ((0,0),(1,1))
 1 | ((1,1),(0,0))
 2 | ((833749,820999),(844362,821001))
 3 | ((100,100),(101,101))
 4 | ((0,0),(1,1),(3,-1))
(5 rows)
 
test=# select * from test  where polygon(pclose(_lines)) @ polygon
'(-2,-2),(85,85)';
 geoid |_lines
---+---
 0 | ((0,0),(1,1))
 1 | ((1,1),(0,0))
(2 rows)
 
test=# select * from test  where polygon(pclose(_lines)) @ polygon
'(-2,-2),(84,85)';
 geoid | _lines
---+
(0 rows)



---(end of broadcast)---
TIP 2: you can get off all lists at once with the unregister command
(send "unregister YourEmailAddressHere" to [EMAIL PROTECTED])

Re: [BUGS] Bug? (geo operator @ )

[Daniel Lau]

Thank you for answering my question.
I made a careless mistake.

regards,
Daniel

On Mon, 22 Dec 2003, Tom Lane wrote:

> Daniel Lau <[EMAIL PROTECTED]> writes:
> > I was to extract the '_lines' (path) if the lines are contained or on by a
> > box-like polygon. The result turns wrong if the box-like polygon is
> > changed from a square (x_max = y_max) to a rectangle (x_max <> y_max).
> 
> The examples you give are not "box-like"; they are in fact just line
> segments.  You need four points to define a box-like polygon.
> 
> AFAICS the quoted example is correct behavior.
> 
>   regards, tom lane
> 


---(end of broadcast)---
TIP 7: don't forget to increase your free space map settings