[GraphHopper] Calculating fastest path with A*/Dijkstra with CH disabled

[Peter K]

Hey,

> >This is called geocoding and not provided by GraphHopper. Although we
> >have some (closed source) prototype we still recommend other existing
> >solutions.
>
> Isn't there a way then to somehow manually find which node/edge ID is
> associated with street name by reading routing data provided from
> graphopper.sh script? I only need to figure out 5-10 street's names
> associated with their edge/node ids so that I could manipulate them
> via hardcoding. I mean, yes, it's that unpractical and basic but
> that's my goal here :)

yes, sure: loop over all edges! This extremely expensive and error-prone
as there are multiple identical named streets even in one city! But you
can find the names:

EdgeIterator iter = getAllEdges();
while (iter.next())
{
      iter.getName()
}

> >Where the last option probably would be the simplest one as there is
> >already a (hidden) method for it in OSMReader called isInBounds or just
> >use OSM tools like osmosis:
> >http://wiki.openstreetmap.org/wiki/Osmosis#Extracting_bounding_boxes
> >
> >Or do you need to define it per request? What is your usecase?
>
> Yes, my usecase would be to define per request: 
> -First request calculates the fastest path 
> -Point A is moving inside the map (GPS tracking on) 
> -Timer should recalculate path each 30s or so

Ok, but why would you need to find a path in a subgraph - to limit
search space? Wouldn't it make more sense to re-compute the whole path
(where you could reuse parts of the old result) or if that is too
expensive you could re-compute a path in a bounding box leading you back
to the original path.


> >* limit the search to only nodes in this area (this is only possible
ifno CH is used)
> >
> how is this possible to implement?

Will work for none CH only. You'll have to tweak the algorithm to accept
only edges which are in the bounds:
edgeFilter = new EdgeFilter() {
   accept(EdgeIteratorState state) {
      base = state.getBaseNode();
      adj = state.getAdjNode();
      int baseLat = graph.getLatitude(base);
      int baseLon = graph.getLatitude(base);
...
      return bbox.contains(baseLat, baseLon) || bbox.contains(adjLat,
adjLon);
   }
}
dijkstra.setEdgeFilter(edgeFilter);

Regards,
Peter.
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