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<div class="moz-cite-prefix">Hi Wesam,<br>
<br>
> do you think that the QueryGraph approach will work for
multiple vehicles distributed on the graph?<br>
<br>
It could be that the QueryGraph is not the most performant
solution, but if you only have a few hundreds or even thousands,
it might work. I have tested it up to 10K without having problems
but it could be that there are problems for more locations. <br>
<br>
Also the QueryGraph is intended to be as much lightweight as
possible so 'frequent throw aways' should be fine.<br>
<br>
> will try to find the closest street node to the vehicle and
mark it (in a seperate hashtable) <br>
> to be a vehicle representative node and will be handled
differently in the routing algorithm<br>
<br>
For that just use QueryResult.getClosestNode obtained from the
location index.<br>
<br>
<br>
> The disadvantage here is clearly that the street node might
be far away from the vehicle position. <br>
<br>
Yes, you'll need to calculate the splitted weight, geometry etc
... which is done in QueryGraph already<br>
<br>
> Later on I might think of splitting the street edge. I
thought this might be easier to start with. what do you think? <br>
<br>
Yes, this is exactly what we are doing in QueryGraph and it is not
easy :)<br>
Assume you have multiple vehicles on the same edge ... this should
be all supported from QueryGraph already. Probably the first trial
could be indeed with QueryGraph and switch to something else if
this won't work or is too slow.<br>
<br>
Would be interesting to make the QueryGraph useful for this kind
of use case too.<br>
<br>
Regards,<br>
Peter<br>
<br>
On 24.07.2015 11:17, wesam Herbawi wrote:<br>
</div>
<blockquote
cite="mid:CALqm3gBE1=hwr961HuoFqoOVX5H++cTg89KpgBUW=YasMxidKA@mail.gmail.com"
type="cite">
<div dir="ltr">Many thanks Peter,
<div>do you think that the QueryGraph approach will work for
multiple vehicles distributed on the graph? I am thinking of
updating the QueryGraph on regular basis, e.g. every 10
minutes, not per query.</div>
<div><br>
</div>
<div><br>
</div>
<div>Away from the QueryGraph approach, as a start, I will try
to find the closest street node to the vehicle and mark it (in
a seperate hashtable) to be a vehicle representative node and
will be handled differently in the routing algorithm. The
disadvantage here is clearly that the street node might be far
away from the vehicle position. Later on I might think of
splitting the street edge. I thought this might be easier to
start with. what do you think? </div>
<div><br>
</div>
<div><br>
</div>
</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">On 23 July 2015 at 20:38, Peter <span
dir="ltr"><<a moz-do-not-send="true"
href="mailto:graphhopper@gmx.de" target="_blank">graphhopper@gmx.de</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000">
<div>Hi anonymous,<span class=""><br>
<br>
<br>
> So during the time of creating the street graph,
the vehicles' nodes will be <br>
> considered and have their own indecies in the
original nodes array. <br>
<br>
</span> Yes, that was what I meant.<br>
<br>
But now I know better what you mean with this kind of
car sharing. Then it is indeed a bit different and I
would assign the position to the two nodes of the edge,
but associated with a different weight in the algorithm
reflecting the precise position and skipping node(s) in
case of one ways.<br>
<br>
The problematic is indeed very similar to the
"QueryGraph vs. precise GPS routing" discussion:<br>
<a moz-do-not-send="true"
href="https://github.com/graphhopper/graphhopper/issues/27"
target="_blank">https://github.com/graphhopper/graphhopper/issues/27</a><br>
<a moz-do-not-send="true"
href="https://github.com/graphhopper/graphhopper/pull/115"
target="_blank">https://github.com/graphhopper/graphhopper/pull/115</a><br>
<br>
<br>
<div><span class="">> sorry for the long discussion.
just trying to understand the alternatives before
going further.<br>
<br>
</span> No problem. Interesting use case.<br>
<br>
</div>
Regards,<br>
Peter
<div>
<div class="h5"><br>
<br>
On 23.07.2015 18:52, graphhopper newbie wrote:<br>
</div>
</div>
</div>
<div>
<div class="h5">
<blockquote type="cite">
<div dir="ltr">If I correctly understand you, this
would solve the problem of adding vehicle
representative nodes. So during the time of
creating the street graph, the vehicles' nodes
will be considered and have their own indecies in
the original nodes array. However, what I miss is
how to maintain the dynamic edges. when a vehicle
is parked somewhere, an edge has to be added to
connect it to the closest street node and the
previous connecting edges have to be removed.
<div><br>
</div>
<div><br>
</div>
<div>Another interpretation that might be what you
mean is that not to add vehicle nodes at all and
consider the closest original street node to the
vehicle to be the vehicle representative node
and to add it to the data structure you
mentioned earlier. if this is the case then I
would miss some information I was planning to
model using the edge connecting the street node
and the vehicle node (still can be done
implicitly) </div>
<div><br>
</div>
<div>sorry for the long discussion. just trying to
understand the alternatives before going
further.</div>
<div><br>
</div>
<div>Regards</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">On 23 July 2015 at
16:58, Peter <span dir="ltr"><<a
moz-do-not-send="true"
href="mailto:graphhopper@gmx.de"
target="_blank">graphhopper@gmx.de</a>></span>
wrote:<br>
<blockquote class="gmail_quote"
style="margin:0 0 0 .8ex;border-left:1px
#ccc solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000">
<div>I would just mark (in a different
data structure) that these nodes are
special e.g. in an array or
(RAM)DataAccess which is more complex
but also storable and scales to GB.<br>
<br>
This way you don't need to remove/re-add
them and instead can just remove the
marker from the array. A lot easier IMO.<br>
<br>
Regards,<br>
Peter<span><br>
<br>
On 23.07.2015 16:17, graphhopper
newbie wrote:<br>
</span></div>
<span>
<blockquote type="cite">
<div dir="ltr">Thanks for the reply,
<div>The use case makes the
situation dynamic. Assume that you
have free floating carsharing
vehicles. Let us assume that these
vehicles can be parked
everywehere. what I wanted to do
is to periodically link these
vehicles to the closest nodes in
the original street graph (remove
old links when vehicles change
their positions). This way the
vehicles will be represented as
nodes in the graph and routing
will be easier later. My routing
algorithm has to be able to switch
from walk to drive mode when such
vehicle node is found. the goal is
to have walk-drive-walk route in
one Dijkstra run.</div>
<div><br>
</div>
<div>Regards,</div>
</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">On 23 July
2015 at 15:47, Peter <span
dir="ltr"><<a
moz-do-not-send="true"
href="mailto:graphhopper@gmx.de"
target="_blank">graphhopper@gmx.de</a>></span>
wrote:<br>
<blockquote class="gmail_quote"
style="margin:0 0 0
.8ex;border-left:1px #ccc
solid;padding-left:1ex">
<div bgcolor="#FFFFFF"
text="#000000">
<div>Hi,<br>
<br>
you can, but there is
currently no way to remove
such edges (efficiently).<br>
<br>
Another workaround would be
to use the QueryGraph for
this like we use to
introduce virtual nodes and
edges to incorporate the
start+end GPS point into the
graph. But never tried this.<br>
<br>
Why not always add all such
points to the graph, why is
a dynamic scenario needed
here?<br>
<br>
Kind Regards,<br>
Peter
<div>
<div><br>
<br>
On 23.07.2015 15:42,
graphhopper newbie
wrote:<br>
</div>
</div>
</div>
<blockquote type="cite">
<div>
<div>
<div dir="ltr">Hi
everybody,
<div>I am wondering if
I can add nodes and
edges to the graph
after its creation
in a dynamic way. I
need this
functionality to
deal with dynamic
scenarios like
representing
available
bikesharing/carsharing
points which changes
often. The simpist
case I need is to
add an edge from a
newly added node (
representing the
available bike) to
the closest node in
the graph and the
reverse edge. i.e.
from the closest
node to the the bike
node. </div>
<div><br>
</div>
<div>Thank you very
much,<br>
</div>
</div>
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