neo4j cypher query to find root node

[vipul jain]

hi Guys,

if I have following tree :

                                    A                                              A1

                                  /   \                                             /     \

                                B    C                                         B1    C1

                             /    \   /   \                                      /    \      /    \

                          D    E F    G                              D1 E1    F1  G1

                          :                                                 :

                          : n length                                    : n length

                          :                                                  :

                          /  \                                               /  \

                         Y   Z                                          Y1   Z1

in this tree I know the id of Y, Z, Y1, Z1.

I want to write the cypher query which return the root node A A1 only. Relationship between each node is like A is PARENT_OF B and so on.

Can one help me on this .

Thanks

vipul

[Wes Freeman]

something like this:

START y=node(id)
MATCH (y)<-[:PARENT_OF*]-(root)
WHERE NOT (root)<-[:PARENT_OF]-()
RETURN root

[Koen Kleingeld]

this will give the degree,indegree and outdegree  of all nodes .... indegree=0 is your root

(code thanks to wes/michael some days ago in one of my posts)

match (n)-[r]-()
with n, sum(case when startnode(r) = n then 1 else 0 end) as outdegree, sum(case when endnode(r) = n then 1 else 0 end) as indegree
return id(n),n.nodename as nodename, outdegree, indegree, outdegree+indegree AS degree
order by indegree asc

this only indegree 0

match (n)-[r]-()
with n, sum(case when endnode(r) = n then 1 else 0 end) as indegree where indegree=0
return id(n),n.nodename as nodename, indegree
order by indegree asc

reg koen

2013/10/14 Wes Freeman <freem...@gmail.com>

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Groeten / Best Regards,

Koen

[Michael Hunger]

Yup

Michael

[vipul jain]

Hi koen,

kindly check my this query, is there any problem because it gives me no result

START n=node:users(CURR_DUNS_NUMBER="832311906")

match (n)-[r]-()
with n, sum(case when endnode(r) = n then 1 else 0 end) as indegree where indegree=0
return id(n),n.nodename as nodename, indegree
order by indegree asc

i think in place of r i have put PARENT_OF. because this is my relationship.

kindly modify your query with PARENT_OF relationship

Thanks,
Vipul


START n=node:users(CURR_DUNS_NUMBER="832311906")
match (n)-[PARENT_OF]-()

with n, sum(case when endnode(r) = n then 1 else 0 end) as indegree where indegree=0
return id(n),n.nodename as nodename, indegree
order by indegree asc

Thanks,
Vipul

[Koen Kleingeld]

START n=node(*)

match (n)-[r]-()
with n, sum(case when endnode(r) = n then 1 else 0 end) as indegree where indegree=0
return id(n),n.nodename as nodename, indegree
order by indegree asc

2013/10/15 vipul jain <pansariv...@gmail.com>

[Wes Freeman]

Are you still trying to find the root?

Wes

[Koen Kleingeld]

lol

2013/10/15 Wes Freeman <freem...@gmail.com>