[GraphHopper] There must be bug on the subnetwork removal

[John Zhao]

Hi Peter,

Thanks.
Actually I only have 1 flagEncoder in the EncodingManager.
The call is exact same, preparation.findSubnetworks()

preparation.findSubnetworks() using edgeFilter which is also from singleEncoder.


*Best Regards,*
*ZhiQiang ZHAO*

On Sun, Jul 26, 2015 at 7:56 AM, Peter <graphhopper at gmx.de> wrote:

>  Hi John,
>
> it should not be related to calling these method twice. It is just one
> time where you calculate the subnetworks independent of any FlagEncoder or
> direction via findSubnetworks and the second pass is FlagEncoder- and
> access-dependent via removeDeadEndUnvisitedNetworks.
>
> Regards,
> Peter
>
>
> On 24.07.2015 21:16, John Zhao wrote:
>
> Hi Peter,
>
>  I am still confused.
> at first we call
> map = findSubnetworks();
>
>  after the cleanup, we call the same method in Graphhopper.
>
> int remainingSubnetworks = preparation.findSubnetworks().size();
>
>  Why the subnetwork was recognized the latter time, but not the first time?
>
> we remove some edges make it not connected?
>
>
>  *Best Regards,*
> *ZhiQiang ZHAO*
>
> On Thu, Jul 23, 2015 at 2:22 PM, Peter <graphhopper at gmx.de> wrote:
>
>>
>>  Hi ZhiQiang,
>>
>> yes, according to the wiki this is wrongly mapped:
>> * Avoid tagging highway intersections as that does not make clear which
>> way has the impediment. *
>>
>> http://wiki.openstreetmap.org/wiki/Tag:barrier%3Dgate
>>
>> Peter
>>
>>
>> On 23.07.2015 23:16, John Zhao wrote:
>>
>> Hi Peter,
>>
>>  Maybe the following one related with
>> https://github.com/graphhopper/graphhopper/issues/388#issuecomment-88066385
>>
>>
>>  I have a look at 37.32611992939085,-121.9961998312816.
>> It seesm related with barrier=gate at intersection.
>> http://www.openstreetmap.org/node/1126492194
>>
>>  *Best Regards,*
>> *ZhiQiang ZHAO*
>>
>> On Thu, Jul 23, 2015 at 2:11 PM, Peter <graphhopper at gmx.de> wrote:
>>
>>>
>>>  There are two types of subnetworks and the smaller ones seems to be
>>> 'one-way subnetworks' which means they are eg. only reachable as
>>> destination or start. But if you would start from a destination-only
>>> subnetwork you'll get 'not found' for all points outside of this network.
>>>
>>> Regards,
>>> Peter
>>>
>>>
>>> On 23.07.2015 23:03, John Zhao wrote:
>>>
>>>  Interesting,
>>> when I increase minOnewayNetworkSize from 20 to 50, the following two
>>> disappeared.
>>>  subnetwork start from: 37.32611992939085,-121.9961998312816 size: 24
>>> subnetwork start from: 37.78373608999855,-122.25065187925067 size: 34
>>>
>>>  *Best Regards,*
>>> *ZhiQiang ZHAO*
>>>
>>> On Thu, Jul 23, 2015 at 1:55 PM, John Zhao <johnthu at gmail.com> wrote:
>>>
>>>> Hi,
>>>>
>>>>  I tried car flag encoder with following parameter on San Francisco
>>>> bay area data from mapzen.
>>>>
>>>> https://s3.amazonaws.com/metro-extracts.mapzen.com/san-francisco-bay_california.osm.pbf
>>>>
>>>>  minNetworkSize=200
>>>> minOnewayNetworkSize=20
>>>>
>>>>  I printed all the remaining subnetworks.
>>>>  edges: 591932, nodes 437420, there were 3496 subnetworks. removed
>>>> them => 13121 less nodes. Remaining subnetworks:5
>>>> The remaining subnetworks are:
>>>> subnetwork start from: 37.32611992939085,-121.9961998312816 size: 24
>>>> subnetwork start from: 37.56018439442332,-122.30257814308803 size:
>>>> 436637
>>>> subnetwork start from: 37.78373608999855,-122.25065187925067 size: 34
>>>> subnetwork start from: 38.180185962770565,-121.70631393878864 size: 301
>>>> subnetwork start from: 37.85717050411933,-122.07633641532816 size: 424
>>>>
>>>>  I don't understand why there is still subnetwork less than 200 nodes.
>>>>
>>>>  I have a look at 37.32611992939085,-121.9961998312816.
>>>> It seesm related with barrier=gate at intersection.
>>>> http://www.openstreetmap.org/node/1126492194
>>>>
>>>>   *Best Regards,*
>>>> *ZhiQiang ZHAO*
>>>>
>>>
>>>
>
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