Re: [jgrapht-users] Extracting parts of the graph

[J K. <j.k...@gm...>]

Currently there's no build-in function which can do that automatically for
you. We are currently making this functionality available somewhere in the
next few weeks, see Pull Request:
https://github.com/jgrapht/jgrapht/pull/423

In the mean time, to get the desired behavior, you could implement your own
DepthFirstSearch iterator. Or more conveniently, just copy mine:
https://github.com/jkinable/jgrapht/blob/95daef5a6826818d00e113ac610415a763c5aee0/jgrapht-core/src/main/java/org/jgrapht/traverse/DepthFirstIterator.java

This iterator has a new function getDepth(V v) which allows you to query
the depth of a specific node (after the DFS completes, or after the node
has been visited). So in order to query all nodes at a certain depth, you
could write an additional function:
//cache the nodes at a given depth
Map<Integer,Set<V>> depthMap=new HashMap<>();
for(V v : graph.vertexSet()){
 int depth=dfs.getDepth(v);
 if(!depthMap.containsKey(depth))
   depthMap.put(depth, new HashSet<V>());
 depthMap.get(depth).add(v);
}
Now you can easily query all nodes at a given depth: depthMap.get(3);

On Thu, Sep 14, 2017 at 1:00 PM, Bobi Adji Andov <bob...@gm...>
wrote:

> Hello all,
>
> I am a new user to JGraphT and as every other newbie I am running into
> ideas that I would like to solve with this library, but I am still not sure
> how to do that.
>
> I am building a directed graph and I am wandering is there a way to get
> all the nodes at certain depth (starting from a vertex). For example
> something like get all nodes at depth 3 from certain vertex.
>
> Thanks in advance,
> Slobodan
>
> --
>
>
>
> *Slobodan Adji-Andovskype:bobiadziandov*
>
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