Hi,
Michael Hunger separately provided me this query - which is a prototype
query which looks like it will do what I want. It includes features of
Cypher I was not familiar with (particularly unwind):
> |.... match path = shortestPath( (n)-[*]->(m) ) unwind nodes(path) as n
> with collect(distinct n) as nodes unwind rels(path) as r return
> collect(distinct r), nodes|
If I understand it correctly, this returns a single tuple with two elements:
1. List of all individual relationships (no duplicates)
2. List of all individual nodes (no duplicates)
I'll have to try this out!
I kind of wonder how this gets mapped into py2neo - what type are the
tuple elements -- list(Relationship) and list(Node) or something like
that...
*Nigel?*
I know my code won't currently handle this - but I can fix that ;-)
-- Alan
On 04/25/2016 08:28 AM, Alan Robertson wrote:
> Hi,
>
> Is there a way to specify a query which returns an intact subgraph?
>
> For example:
>
> starting from node "X" (by some specification), return the subgraph
> reachable through a collection of relationship types {T}, through some
> maximum distance (d), return a JSON representation of this subgraph -
> possibly with some WHERE specifications, but possibly not. In our
> nodes we include a nodetype in every node, we might want to say "WHERE
> node.nodetype IN {N}" as our where clause.
>
> Result should be in some JSON graph format, perhaps like JSON Graph
> Format (JGF) http://jsongraphformat.info/ or
> https://github.com/bruth/json-graph-spec.
>
> This is exactly what's needed for visualization of a subgraph from a
> Javascript program. Since Neo4j graphs are often huge, even monstrous,
> having a query that does this would be incredibly handy...
>
> Otherwise you have to go through and put this graph together a piece
> at a time (or so it seems to me).
>
> I think I can write a query which returns all the paths through this
> subgraph, but then I have to do the duplication elimination and so on
> myself. A single node might be returned many times in the possible
> paths result. Not an ideal situation...
>
> This seems like a very common thing to want to do...
>
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