[GraphHopper] There must be bug on the subnetwork removal
John Zhao
johnthu at gmail.com
Wed Jul 29 09:44:31 UTC 2015
Hi Peter,
There are a lot of SCC with only 1 node, like:
http://www.openstreetmap.org/node/1707762331
http://www.openstreetmap.org/node/386885888
http://www.openstreetmap.org/node/364825950
Step 4 is only to findSubnetwork(), and print some info, not removal them.
So, step 4 is optional.
Now I only understand why this happen. :(
*Best Regards,*
*ZhiQiang ZHAO*
On Wed, Jul 29, 2015 at 2:28 AM, Peter <graphhopper at gmx.de> wrote:
> Hi ZhiQiang,
>
> > And the http://www.openstreetmap.org/node/678314919 itself is a SCC.
> size is 1.
>
> It shouldn't be a SCC im my opinion - is there a bug?
> If it is not a bug - do you have a suggestion for this, like avoiding step
> 4?
>
> Regards,
> Peter
>
>
>
> On 29.07.2015 11:18, John Zhao wrote:
>
> Hi Peter,
>
> The parameter I set are minOnewayNetworkSize = 20, minNetworkSize = 200
>
> on step 3, despite the node http://www.openstreetmap.org/node/678314919,
> the inside island is a SCC, and the size is larger than 20.
> So, this island is kept, instead of removal.
> And the http://www.openstreetmap.org/node/678314919 itself is a SCC. size
> is 1. Then it was removed.
>
> Then on step 4, the island is recognized as a subnetwork, which has size
> less than 200.
>
> *Best Regards,*
> *ZhiQiang ZHAO*
>
> On Wed, Jul 29, 2015 at 1:04 AM, Peter <graphhopper at gmx.de> wrote:
>
>> Hi ZhiQiang,
>>
>> you mean the oneway procedure (step 3) removes nodes+edges leading to
>> further normal subnetwork removal in step 4? This should not happen. The
>> subnetwork should be removed already in step 3.
>>
>> > On step 2, although there is a gate
>> http://www.openstreetmap.org/node/703042503
>> > on http://www.openstreetmap.org/way/6374339
>> > And gate block that edge.
>>
>> Because of this gate the island is a oneway subnetwork (!) and should
>> get entirely removed in step 2 IMO.
>>
>> > On step 3, a very important point are removed due to oneway
>>
>> If just one edge/node is removed there is something wrong. The whole
>> island should be removed.
>>
>> Kind Regards,
>> Peter
>>
>>
>> On 29.07.2015 09:50, John Zhao wrote:
>>
>> Hi Peter,
>>
>> I know the difference between subnetworks and oneway-subnetworks.
>> I am talking about the step 2 and step 4, not step 3.
>>
>> step 2 and step 4 are both findSubnetwork() with the same parameter.
>> minOnewayNetworkSize = 20, minNetworkSize = 200
>>
>> I think I figure out why this discrepancy occurs.
>> One case is a island in SF bay area. The island has 2 oneway roads
>> connected to the main network.
>> http://www.openstreetmap.org/way/53726398
>> http://www.openstreetmap.org/way/6374339
>>
>> On step 2, although there is a gate
>> http://www.openstreetmap.org/node/703042503 on
>> http://www.openstreetmap.org/way/6374339
>> And gate block that edge.
>> The other oneway is connected http://www.openstreetmap.org/way/53726398.
>> So, this island is connected to the whole network.
>>
>> On step 3, a very important point are removed due to oneway:
>> http://www.openstreetmap.org/node/678314919
>>
>> Then on step 4, the island are not connected to the main network.
>>
>> *Best Regards,*
>> *ZhiQiang ZHAO*
>>
>> On Tue, Jul 28, 2015 at 11:12 PM, Peter <graphhopper at gmx.de> wrote:
>>
>>> Hi ZhiQiang,
>>>
>>> hmmh, not sure if I understand what is unknown at your side.
>>>
>>> Subnetworks are different things than oneway-subnetworks. For example
>>> 4-5 is a oneway subnetwork if connect with a oneway to the main graph only:
>>> mainGraph->4-5
>>>
>>> And this cannot be detected in step 2.
>>>
>>> Please have a look at the unit tests to see more examples for the
>>> different scenes
>>>
>>> Regards,
>>> Peter
>>>
>>>
>>> On 28.07.2015 20:05, John Zhao wrote:
>>>
>>> Hi Peter,
>>>
>>> the result I posted is not the result of oneway-subnetwork procedure.
>>>
>>> The total procedures include:
>>> 1. remove zero-degree node
>>> 2. findSubnetwork
>>> 3. oneway-subnetwork procedure
>>> 4. findSubnetwork again on graphhopper.cleanup()
>>>
>>> My question is, why those islands are recognized on step 4, but not on
>>> step 2?
>>>
>>>
>>>
>>> *Best Regards,*
>>> *ZhiQiang ZHAO*
>>>
>>> On Tue, Jul 28, 2015 at 12:02 AM, Peter <graphhopper at gmx.de> wrote:
>>>
>>>> Hi ZhiQiang,
>>>>
>>>> I think it is because both networks are oneway subnetworks not found by
>>>> the normal subnetwork procedure (but by the oneway-subnetwork procedure)
>>>> and you defined the oneway minimum size to 20
>>>>
>>>> Regards,
>>>> Peter
>>>>
>>>>
>>>> On 28.07.2015 03:13, John Zhao wrote:
>>>>
>>>> Hi Peter,
>>>>
>>>> What I do is:
>>>> 1. minOnewayNetworkSize = 20, minNetworkSize = 200
>>>> 2. build san francisco bay area osm data
>>>> 3. I print out the subnetworks result of the second call.
>>>>
>>>> int remainingSubnetworks = preparation.findSubnetworks().size();
>>>>
>>>> 4. I found the subnetwork has some smaller than 200, like:
>>>>
>>>> subnetwork start from: 37.32611992939085,-121.9961998312816 size: 24
>>>>
>>>> subnetwork start from: 37.78373608999855,-122.25065187925067 size: 34
>>>>
>>>> 5. I can't understand why the subnetworks with 24 nodes and 34 nodes are not removed by preparation.doWork();
>>>>
>>>> It call the same method:
>>>>
>>>> Map map = this.findSubnetworks();
>>>>
>>>>
>>>> *Best Regards,*
>>>> *ZhiQiang ZHAO*
>>>>
>>>> On Mon, Jul 27, 2015 at 12:54 PM, Peter <graphhopper at gmx.de> wrote:
>>>>
>>>>> Hi John,
>>>>>
>>>>> sorry, I do not understand your problem or question here. Would you
>>>>> describe it again step by step for me :) ?
>>>>>
>>>>> Kind Regards,
>>>>> Peter
>>>>>
>>>>>
>>>>> On 27.07.2015 21:45, John Zhao wrote:
>>>>>
>>>>> 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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