[GraphHopper] There must be bug on the subnetwork removal

[Peter]

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