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

[Peter]

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
> <mailto: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
>     <mailto: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
>>     <mailto: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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