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<DIV dir=ltr align=left><SPAN class=459435013-15122008><FONT face=Arial
color=#0000ff size=2>Andrew,</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=459435013-15122008><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=459435013-15122008><FONT face=Arial
color=#0000ff size=2>Not sure I understand your question. Are you saying
your street segments are cut such that they only connect at junctions.
Kind of like tiger tlids.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=459435013-15122008><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=459435013-15122008><FONT face=Arial
color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=459435013-15122008><FONT face=Arial
color=#0000ff size=2>And given each intersection, you are trying to find
continguous segments from the intersection?</FONT></SPAN></DIV>
<DIV><SPAN class=459435013-15122008><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=459435013-15122008><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=459435013-15122008><FONT face=Arial color=#0000ff
size=2>e.g.</FONT></SPAN></DIV>
<DIV><SPAN class=459435013-15122008><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=459435013-15122008><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN
class=459435013-15122008>----------- ------------- --------------- <FONT
face=Arial color=#0000ff size=2>Intersection --------------------------
------------------------------- -----------------</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=459435013-15122008><FONT face=Arial
color=#0000ff
size=2> t3
t2 t1
s3
s4
sn</FONT></SPAN></DIV>
<DIV><SPAN class=459435013-15122008><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=459435013-15122008><FONT face=Arial color=#0000ff
size=2> |a1</FONT></SPAN></DIV>
<DIV><SPAN class=459435013-15122008><FONT face=Arial color=#0000ff
size=2> |a2</FONT></SPAN></DIV>
<DIV><SPAN class=459435013-15122008><FONT face=Arial color=#0000ff
size=2>
|an</FONT></SPAN></DIV>
<DIV><SPAN class=459435013-15122008><FONT face=Arial color=#0000ff size=2>So you
would keep on collecting segments as long as they are connected to the previous
ones?</FONT></SPAN></DIV>
<DIV><SPAN class=459435013-15122008><FONT face=Arial color=#0000ff
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=459435013-15122008><FONT face=Arial color=#0000ff
size=2>Thanks,</FONT></SPAN></DIV>
<DIV><SPAN class=459435013-15122008><FONT face=Arial color=#0000ff
size=2>Regina</FONT></SPAN></DIV>
<DIV dir=ltr align=left><FONT face=Arial color=#0000ff size=2></FONT><BR></DIV>
<DIV class=OutlookMessageHeader lang=en-us dir=ltr align=left>
<HR tabIndex=-1>
<FONT face=Tahoma size=2><B>From:</B>
postgis-users-bounces@postgis.refractions.net
[mailto:postgis-users-bounces@postgis.refractions.net] <B>On Behalf Of
</B>Andrew Ross<BR><B>Sent:</B> Saturday, December 13, 2008 11:05
AM<BR><B>To:</B> postgis-users@postgis.refractions.net<BR><B>Subject:</B>
[postgis-users] Crossing roads<BR></FONT><BR></DIV>
<DIV></DIV>
<DIV style="FONT-SIZE: 12pt; FONT-FAMILY: times new roman,new york,times,serif">
<DIV><BR>
<P><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">Hi
Everybody,</SPAN></FONT></P>
<P><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">I hope I'm posting to
the right location (I just subscribed to this list). I have sent this
question before but have not seen it listed anywhere yet.<BR></SPAN></FONT></P>
<P><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"><BR></SPAN></FONT></P>
<P><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">In any case, I have a
road network in which all of the street segments are snapped together. I
need to group all of the line segments of two streets that cross each other
(street 1 and street 2 as shown below) into 4 groups of segments defined as all
of those located on either side of the intersection, </SPAN></FONT><FONT
face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">(street segments A,
street segments B, street segments C and street segments D</SPAN></FONT><FONT
face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">, as shown at the
bottom</SPAN></FONT><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">)</SPAN></FONT><FONT
face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">.
</SPAN></FONT></P>
<P><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"></SPAN></FONT> </P>
<P><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">Can anybody give me a
high level idea of what functions / methods can be used to achieve this?
</SPAN></FONT></P>
<P><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"></SPAN></FONT> </P>
<P><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">I¢ve gotten as far as
identifying the 4 segments actually connected to the intersection using the
ST_Intersection function. </SPAN></FONT></P>
<P><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"></SPAN></FONT> </P>
<P><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">How would I get all
other segments connected to these 4? </SPAN></FONT></P>
<P><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"></SPAN></FONT> </P>
<P><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">Do I have to write a
recursive function using ST_Touches ? I¢d rather not if there is a more
elegant way of doing this.</SPAN></FONT></P>
<P><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"></SPAN></FONT> </P>
<P><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">Thanks in
advance,</SPAN></FONT></P>
<P><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">Andrew</SPAN></FONT></P>
<P><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"></SPAN></FONT> </P>
<P><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"></SPAN></FONT> </P>
<P><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"></SPAN></FONT> </P>
<P><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"> <WBR>
1</SPAN></FONT></P>
<P><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"> <WBR>
1</SPAN></FONT></P>
<P><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"> <WBR>
1</SPAN></FONT></P>
<P><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"> <WBR>
1</SPAN></FONT></P>
<P><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">
222222222222 X 22222222222222</SPAN></FONT></P>
<P><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"> <WBR>
1</SPAN></FONT></P>
<P><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"> <WBR>
1</SPAN></FONT></P>
<P><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"> <WBR>
1</SPAN></FONT></P>
<P><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"> <WBR>
1</SPAN></FONT></P>
<P><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"></SPAN></FONT> </P>
<P><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"></SPAN></FONT> </P>
<P><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"></SPAN></FONT> </P>
<P><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"> <WBR>
A</SPAN></FONT></P>
<P><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"> <WBR>
A</SPAN></FONT></P>
<P><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"> <WBR>
A</SPAN></FONT></P>
<P><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"> <WBR>
A</SPAN></FONT></P>
<P><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">
BBBBBBBBBBXCCCCCCCCCCC</SPAN></FONT></P>
<P><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"> <WBR>
D</SPAN></FONT></P>
<P><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"> <WBR>
D</SPAN></FONT></P>
<P><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"> <WBR>
D</SPAN></FONT></P>
<P><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"> <WBR>
D</SPAN></FONT></P>
<P><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"></SPAN></FONT> </P>
<P><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"></SPAN></FONT> </P>
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