[postgis-users] Path to closest neighbor

[Stephen Woodbridge]

You need to read up on pgRouting and probably join the pgRouting list

http://pgrouting.postlbs.org/
http://lists.postlbs.org/mailman/listinfo/pgrouting-users

-Steve

Nalin C wrote:
> Also, can you please suggest me the functions that can be used for points 2
> and 3 ?  I'm totally a newbie to postgis. 
> 
> In point 2, it would be great if the path can start from in front of the
> hospital, instead a vertex in roads table.
> 
> 
> 
> Nalin C wrote:
>> Hi Steve,
>>
>> Thank you for the quick reply.
>>
>> I observed that the results returned by :
>>
>> select name, the_geom from hospitals order by
>> distance_sphere(setsrid(makepoint(79.877778, 6.914722), 4326), the_geom)
>> asc limit 3; 
>>
>> are not the closest hospitals to the given accident point. I'm not sure
>> what has gone wrong.
>>
>>
>> Thanks,
>>
>> Nalin
>>
>>
>>
>> Stephen Woodbridge wrote:
>>> Nalin C wrote:
>>>> Hi,
>>>>
>>>> I have two tables for roads and hospitals. I'm looking for suitable
>>>> pgrouting function(s) for following scenario.
>>>>
>>>> Given the accident point (in point geometry), finding the least distant
>>>> hospital and draw the path.
>>>>
>>>> Following functionality is needed.
>>>>
>>>> 1. One end of the drawn path needs to start from in front of the closest
>>>> hospital (which is in hospitals table).
>>>> 2. Path needs to stop from the accident point on road.
>>>>
>>>> I'm new to pgrouting and appreciate your help.
>>> You have a few discrete tasks. Assuming you have the location of the 
>>> accident:
>>>
>>> 1) Select say the three closest hospitals based on straight line 
>>> distance. (x,y) is the location of the accident.
>>>
>>> select name, the_geom from hospitals where order by 
>>> distance_sphere(setsrid(makepoint(x,y), 4326), the_geom) asc limit 3;
>>>
>>> 2) then use pgRouting to use the Hospital location as start and the 
>>> accident as end and comput the routes
>>>
>>> 3) compare the routed distances and select the shortest.
>>>
>>> -Steve W
>>> _______________________________________________
>>> postgis-users mailing list
>>> postgis-users at postgis.refractions.net
>>> http://postgis.refractions.net/mailman/listinfo/postgis-users
>>>
>>>
>>
>