i follow the algo in the wiki page below: So during while loop, i remove a
node n from s and traversal each path(depth 1). and remove this path from
graph. I can set property to this relationship like visited. but how to
check no other incoming edges into node m. Does this mean i have make
traversal from m inside the traversal from n?
L ← Empty list that will contain the sorted elements
S ← Set of all nodes with no incoming edges*while* S is non-empty *do*
remove a node n from S
add n to *tail* of L
*for each* node m with an edge *e* from n to m *do*
remove edge e from the graph
*if* m has no other incoming edges *then*
insert m into S*if* graph has edges *then*
return error (graph has at least one cycle)*else*
return L (a topologically sorted order)
On Wednesday, June 4, 2014 12:35:15 AM UTC-7, TC wrote:
>
> The graph maybe has loop inside and multiple source node(no incoming
> edges).
> Even using traversal description (Uniqueness.Relationship-Global), it will
> need a starting node from users to begin. So it cannot deal with multiple
> source node graph.
> like figure in this wiki page:
> http://en.wikipedia.org/wiki/Topological_sorting
> <http://www.google.com/url?q=http%3A%2F%2Fen.wikipedia.org%2Fwiki%2FTopological_sorting&sa=D&sntz=1&usg=AFQjCNGwQKUHMuuQvSbJz27tZZ-2F8wBHA>
>
>
> On Tuesday, June 3, 2014 11:12:21 PM UTC-7, Michael Hunger wrote:
>>
>> You mean in general? I think toposort is only defined for trees? You can
>> ignore the loops though in a traversal description
>> (Uniqueness.Relationship-Global) and in theory start at any random node in
>> the graph to find the topologically first (tree-root).
>>
>>
>> On Wed, Jun 4, 2014 at 6:50 AM, TC <[email protected]> wrote:
>>
>>> Does neo4j has topological sort function for directed graph data(with
>>> loops)?
>>> If I follow
>>> for ( Path position : db.traversalDescription()
>>> .depthFirst()
>>> .relationships( Rels.LIKES, Direction.INCOMING )
>>> .traverse( node ) )
>>> but how to choose the starting node in topo sort order for this graph?
>>>
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>>
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