<br><br><div class="gmail_quote">On Tue, Sep 6, 2011 at 11:52 PM, Charles Galpin <span dir="ltr"><<a href="mailto:cgalpin@lhsw.com">cgalpin@lhsw.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
I have what I consider a bit of a crazy requirement for routing. In addition to being able to influence the route with rules like shortest path, or fastest, etc. I need to also be able to offer alternative routes within a specific mode. So say they want to favor or avoid highways, I need to be able to give them a few alternatives as well.<br>
</blockquote><div><br></div><div>Hi Charles,</div><div><br></div><div>If you're looking for something like the second shortest or third shortest path, etc., this is called k-shortest path.</div><div>But it's not implemented in pgRouting (yet): <a href="http://www.pgrouting.org/rfc/rfc-04.html">http://www.pgrouting.org/rfc/rfc-04.html</a> </div>
<div>Maybe someone wants to do this or want to sponsor the development. </div><div><br></div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<br>
Does anyone have any thoughts on this? I'm pretty sure even google is doing something like showing you fastest versus shortest, or some other weighting between the options they give in their alternate routes.<br></blockquote>
<div><br></div><div>I guess that, as you say, they use different weights for their alternative routes.</div><div>Different routing algorithms shouldn't give you a different result ... then something might be wrong with them ;-)</div>
<div><br></div><div>Daniel</div><div><br></div><div><br></div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<br>
I have not played with any of the routing algorithms other than Dijkstra (for some reason I could never get A* to work for me when I first looked at pgRouting but will revisit it) so I am not sure if I can expect them to give different results (or with shooting star even), given the same weighting.<br>
<br>
The only think I can think of is to throw "blocks" or penalty wieghts in at random locations (or somehow come up with a clever way to pick them) and re-route and take the new paths, but I suspect this will be very crude, and not useful anyway.<br>
<br>
TIA,<br>
charles<br>
<br>
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</blockquote></div><br><br clear="all"><div><br></div>-- <br><span style="font-family:arial, sans-serif;font-size:13px;border-collapse:collapse">Georepublic UG & Georepublic Japan<br>eMail: <a href="mailto:daniel.kastl@georepublic.de" style="color:rgb(66, 99, 171)" target="_blank">daniel.kastl@georepublic.de</a><br>
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