[GraphHopper] Does Graphhopper merge ways with equal flags and name?

[Jan Torben Heuer]

Hi Peter, 

If there is already a merging logic, then I would  ‚only‘ have to disable the name parsing or nameIndex? Do you have a suggestion how I could do that? (If that is too difficult I could also remove all name tags from the osm file, I think).

Just to be clear, my question has nothing to do with saving memory and stuff. That topic was brought up by ZhiQiang ZHAO. I just need a graph with edges from intersection to intersection.

Thanks,

Jan


Am 03.06.2015 um 09:09 schrieb Peter <graphhopper at gmx.de>:

> Hi Jan,
> 
> we do this kind of 'merging' logic already in the import step when deciding what should be handled as tower node and what is a pillar node. Otherwise you'll need as twice as many RAM when copying from one graph to the other.
> 
> 
> > Have you made a experiment to count the number of 2 degree nodes with the equal flags and name in OSM?
> > And then we can know how many edges we can save.
> 
> Yes, this should be done before implementing it :)
> 
> And as the merging logic is currently not 100% optimal, there could be some minor savings even when recognizing the different street names, but I'm unsure if it is worth the effort.
> 
> Issues like #234 or #111 will probably make more difference.
> 
> Kind Regards,
> Peter
> 
> On 02.06.2015 22:35, John Zhao wrote:
>> Hi,
>> 
>> AFAIK, there is no this kind of merging logic here.
>> Wait the answer from Peter.
>> Probably you need to implement it by your own.
>> And it's not easy. 
>> Maybe can be done before import?
>> What you want, is actually convert a tower node to a pillar node.
>> 
>> 
>> Best Regards,
>> ZhiQiang ZHAO
>> 
>> On Tue, Jun 2, 2015 at 1:27 PM, Jan Torben Heuer <jan at komoot.de> wrote:
>> Hi ZhiQiang ZHAO,
>> 
>> Thanks for your quick answer.
>> I have a custom FlagEncoder that imports only very few ways and I don’t need the names. I guess, I have mostly nodes with a degree of two.
>> 
>> Jan
>> 
>> Am 02.06.2015 um 21:53 schrieb John Zhao <johnthu at gmail.com>:
>> 
>>> Hi,
>>> 
>>> Have you made a experiment to count the number of 2 degree nodes with the equal flags and name in OSM?
>>> And then we can know how many edges we can save.
>>> 
>>> I doubt this should be not too much for OSM.
>>> 
>>> Best Regards,
>>> ZhiQiang ZHAO
>>> 
>>> On Tue, Jun 2, 2015 at 11:59 AM, Jan Torben Heuer <jan at komoot.de> wrote:
>>> Hi,
>>> 
>>> Can Graphhopper merge two ways with equal flags and name if there is no intersection between them (no third way connected)?
>>> 
>>> I would like to create a very reduces graph with only few edges. What would be the easiest way to achieve it? I think I would have to disable the nameIndex for instance.
>>> 
>>> Thanks,
>>> 
>>> Jan
>>> 
> 
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