Normally routing problems such as dijkstra/TSP always select the best
route by the length of the route.
Does anybody known a version that selects the route choosen by the node
type as well as the distance covered? The reason that I ask, in cases the
select of the node type is important for example
I am trying to get from node A to F,
I have to possible routes A B C F , A E to F or A D F.
The route A D E is the shortest one, but D is noted number of highway
men/gunfighters living in town.
I am a careful man and would prefer to travel the safest fast route. Is
there a generic solution to this type of problem other than removing D
from the input list of nodes to compare?
Can anybody suggest a different news group where this type of issue could
be raised?
Normally routing problems such as dijkstra/TSP always select the best
route by the length of the route.
Does anybody known a version that selects the route choosen by the node
type as well as the distance covered? The reason that I ask, in cases the
select of the node type is important for example
I am trying to get from node A to F,
I have to possible routes A B C F , A E to F or A D F.
The route A D E is the shortest one, but D is noted number of highway
men/gunfighters living in town.
I am a careful man and would prefer to travel the safest fast route. Is
there a generic solution to this type of problem other than removing D
from the input list of nodes to compare?
Can anybody suggest a different news group where this type of issue could
be raised?
In pgRouting it is trivial to do this by putting a filter on the edges to remove edges or nodes of a particular class(es). Something like:
select * from edges where etype != 'dangerous';
select * from edges a, nodes b where a.source=b.id or a.target=b.id and b.ntype not in ('dangerous', 'dirty');
Thats useful but its not quite what I am looking for.
I can not make a preselection before I start routing, what I am actual
after is a 'rule based selection'
for example before selecting the next node to consider when selecting the
shortest path, I like to apply a set of rules.
Whats the shortest path if I consider this dangerous node.
Whats the shortest path if I consider what to go near this node etc
There are many reasons why should you choose to go near nodes, some may be
more danegrous that others. I can just screen out all the nodes before I
start out.
Dave.
Stephen Woodbridge wrote:
On 4/10/2012 7:22 AM, Dave Potts wrote:
Hi
Normally routing problems such as dijkstra/TSP always select the best
route by the length of the route.
Does anybody known a version that selects the route choosen by the node
type as well as the distance covered? The reason that I ask, in cases
the
select of the node type is important for example
I am trying to get from node A to F,
I have to possible routes A B C F , A E to F or A D F.
The route A D E is the shortest one, but D is noted number of highway
men/gunfighters living in town.
I am a careful man and would prefer to travel the safest fast route. Is
there a generic solution to this type of problem other than removing D
from the input list of nodes to compare?
Can anybody suggest a different news group where this type of issue
could
be raised?
In pgRouting it is trivial to do this by putting a filter on the edges
to remove edges or nodes of a particular class(es). Something like:
select * from edges where etype != 'dangerous';
select * from edges a, nodes b where a.source=b.id or a.target=b.id and
b.ntype not in ('dangerous', 'dirty');
Not sure I’m understanding your problem correctly. But if you can’t exclude data in your query already (Steve’s proposal) you usually do it by modifying costs.
For example if you have points that indicate dangerous spots, you can create a buffer around these points, select road links within these buffers and increase the costs.
Thats useful but its not quite what I am looking for.
I can not make a preselection before I start routing, what I am actual
after is a ‘rule based selection’
for example before selecting the next node to consider when selecting the
shortest path, I like to apply a set of rules.
Whats the shortest path if I consider this dangerous node.
Whats the shortest path if I consider what to go near this node etc
There are many reasons why should you choose to go near nodes, some may be
more danegrous that others. I can just screen out all the nodes before I
start out.
Dave.
Stephen Woodbridge wrote:
On 4/10/2012 7:22 AM, Dave Potts wrote:
Hi
Normally routing problems such as dijkstra/TSP always select the best
route by the length of the route.
Does anybody known a version that selects the route choosen by the node
type as well as the distance covered? The reason that I ask, in cases
the
select of the node type is important for example
I am trying to get from node A to F,
I have to possible routes A B C F , A E to F or A D F.
The route A D E is the shortest one, but D is noted number of highway
men/gunfighters living in town.
I am a careful man and would prefer to travel the safest fast route. Is
there a generic solution to this type of problem other than removing D
from the input list of nodes to compare?
Can anybody suggest a different news group where this type of issue
could
be raised?
In pgRouting it is trivial to do this by putting a filter on the edges
to remove edges or nodes of a particular class(es). Something like:
select * from edges where etype != ‘dangerous’;
select * from edges a, nodes b where a.source=b.id or a.target=b.id and
b.ntype not in (‘dangerous’, ‘dirty’);
Do you have any articles/papers that discuss this kind of solver? I have not come across this or I'm not understanding your use case. As Daniel has mentioned the we typically control selection by modifying the costs. For example, I made a graph that used the angled between the segments as the cost and then created routes of minimum angle. This could be used for example to generate routes for tractor trailer trucks in low maneuverability.
-Steve
On 4/11/2012 4:22 AM, Dave Potts wrote:
Hi Steve,
Thats useful but its not quite what I am looking for.
I can not make a preselection before I start routing, what I am actual
after is a 'rule based selection'
for example before selecting the next node to consider when selecting the
shortest path, I like to apply a set of rules.
Whats the shortest path if I consider this dangerous node.
Whats the shortest path if I consider what to go near this node etc
There are many reasons why should you choose to go near nodes, some may be
more danegrous that others. I can just screen out all the nodes before I
start out.
Dave.
Stephen Woodbridge wrote:
On 4/10/2012 7:22 AM, Dave Potts wrote:
Hi
Normally routing problems such as dijkstra/TSP always select the best
route by the length of the route.
Does anybody known a version that selects the route choosen by the node
type as well as the distance covered? The reason that I ask, in cases
the
select of the node type is important for example
I am trying to get from node A to F,
I have to possible routes A B C F , A E to F or A D F.
The route A D E is the shortest one, but D is noted number of highway
men/gunfighters living in town.
I am a careful man and would prefer to travel the safest fast route. Is
there a generic solution to this type of problem other than removing D
from the input list of nodes to compare?
Can anybody suggest a different news group where this type of issue
could
be raised?
In pgRouting it is trivial to do this by putting a filter on the edges
to remove edges or nodes of a particular class(es). Something like:
select * from edges where etype != 'dangerous';
select * from edges a, nodes b where a.source=b.id or a.target=b.id and
b.ntype not in ('dangerous', 'dirty');