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

[John Zhao]

I go through the logic:
It go through all osmways, and count the occurrence of nodeID.
if nodeID appear only once, it's a pillar node.
otherwise, it's a tower node.

That's it. Do I miss something?


*Best Regards,*
*ZhiQiang ZHAO*

On Wed, Jun 3, 2015 at 11:55 AM, Peter <graphhopper at gmx.de> wrote:

>  Hi,
>
> there is no separate merging logic (although there was in 0.1 or
> something). In OSMReader it is decided when an edge is created and e.g. OSM
> ways are splitted if there are barriers or junctions on the way. So it
> decides whether an osm nodes will be a tower node or just a pillar node
>
> Regards,
> Peter
>
>
> On 03.06.2015 20:35, John Zhao wrote:
>
> Hi Peter,
>
>  Could you tell me where is the merging logic?
> That's interesting.
>
>  *Best Regards,*
> *ZhiQiang ZHAO*
>
> On Wed, Jun 3, 2015 at 12:09 AM, Peter <graphhopper at gmx.de> wrote:
>
>>  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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