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<DIV><FONT face=Arial size=2>There are a couple of organizations using the boost
lib to solve shortest path graphs using Djikstra algorithms as well as the A
Star and TSP. It would not be a stretch to get this code and modify it to use
the min spanning tree code in boost as well. </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I have taken the code and made major performance
enhancements that are currently being tested. So be wary of better ways to
structure the SQL interface to postgis to achieve your goals.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>You can get the base code from <A
href="http://www.cartoweb.org/">http://www.cartoweb.org/</A> that provides
the basic for interfacing with Djisktra in boost if you want more, please
contact me offline and I can send you a package that also implements the AStar
and TSP, along with my performance enhancements.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Rob.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV>----- Original Message ----- </DIV>
<BLOCKQUOTE
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=pramsey@refractions.net href="mailto:pramsey@refractions.net">Paul
Ramsey</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A
title=postgis-users@postgis.refractions.net
href="mailto:postgis-users@postgis.refractions.net">PostGIS Users
Discussion</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Monday, November 06, 2006 1:44
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [postgis-users] minimum
spanning tree?</DIV>
<DIV><BR></DIV>No such thing right now. If someone is interested in the
problem, there is some background here:
<DIV><BR class=khtml-block-placeholder></DIV>
<DIV><<A
href="http://en.wikipedia.org/wiki/Minimum_spanning_tree">http://en.wikipedia.org/wiki/Minimum_spanning_tree</A>></DIV>
<DIV><BR class=khtml-block-placeholder></DIV>
<DIV>P</DIV>
<DIV><BR>
<DIV>
<DIV>On 6-Nov-06, at 3:09 PM, Catherine Morency wrote:</DIV><BR
class=Apple-interchange-newline>
<BLOCKQUOTE type="cite">
<DIV class=Section1>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Hello,<O:P></O:P></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"><O:P></O:P></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">I am a new user of Postgis.
<O:P></O:P></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">I am looking for a function to
compile the length of the shortest string connecting a set of points.
<O:P></O:P></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">There are no network, only
spatial points. I have already compiled the convex hull of these sets of
points and I am looking for another indicator.<O:P></O:P></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"><O:P></O:P></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Thank
you.<O:P></O:P></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"><O:P></O:P></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=silver size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: silver; FONT-FAMILY: Arial">====================================</SPAN></FONT><O:P></O:P></P>
<P class=MsoNormal><EM><B><I><FONT face=Arial color=navy size=2><SPAN
style="FONT-WEIGHT: bold; FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">Catherine
Morency, ing., Ph.D.</SPAN></FONT></I></B></EM><O:P></O:P></P>
<P class=MsoNormal><STRONG><B><FONT face="Arial Narrow" size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: " narrow??="" arial="">Professeure
adjointe</SPAN></FONT></B></STRONG><O:P></O:P></P>
<P class=MsoNormal><STRONG><B><FONT face="Arial Narrow" size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: " narrow??="" arial="">Département des
génies civil, géologique et des
mines</SPAN></FONT></B></STRONG><O:P></O:P></P>
<P class=MsoNormal><STRONG><B><FONT face="Arial Narrow" size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: " narrow??="" arial="">École
Polytechnique de Montréal</SPAN></FONT></B></STRONG><O:P></O:P></P>
<P class=MsoNormal><STRONG><B><FONT face="Arial Narrow" size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: " narrow??="" arial="">Groupe
MADITUC</SPAN></FONT></B></STRONG><O:P></O:P></P>
<P class=MsoNormal><STRONG><B><FONT face="Arial Narrow" size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: " narrow??="" arial="">(514) 340-4711
p.4502</SPAN></FONT></B></STRONG><O:P></O:P></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"><A
href="mailto:cmorency@polymtl.ca"><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt; FONT-FAMILY: " roman??="" new=""
times="">cmorency@polymtl.ca</SPAN></FONT></A></SPAN></FONT><O:P></O:P></P>
<P class=MsoNormal><FONT face=Arial color=silver size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: silver; FONT-FAMILY: Arial">====================================</SPAN></FONT><O:P></O:P></P>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"><O:P></O:P></SPAN></FONT></P></DIV>
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