[Neo4j] [Cypher] Retrieve all nodes which are not related to a specific node

[Marc de Verdelhan]

Hello,

I have the following graph: http://tinyurl.com/893tzu5

Then when I execute this query: START gp=node(6) MATCH gp-[:B]->c<-[:B]-mp<-[:SW|G]-u WHERE u.name <> "u1" RETURN mp

... it returns p1 and p2.

Could you explain why I'm getting "p1"?

Or in other terms: I would like to remove p1 from these results because this node is related to a node whose "name" property is "u1".

Cheers,

Marc

[Michael Hunger]

b/c there are two paths along which you can reach u1 and you output all the paths.

Michael

[Marc de Verdelhan]

Ok. I wasn't thinking in graph traversal way.

So now, as I tried to do with my query: starting from gw1, I want to retrieve all the nodes which are related to c1 except those which are related to at least one node whose the "name" property equals "u1". What would be the query for that?

Cheers,

Marc

[Michael Hunger]

Marc,

the best I came up with is:

START gp=node(6) MATCH gp-[:B]->c<-[:B]-mp<-[:SW|G]-u with mp, collect(u) as us where NONE(n in us where n.name ='u1') return mp

http://tinyurl.com/7x8t3cb

But perhaps Andrés has better insights.

Michael

[Andres Taylor]

On Mon, May 7, 2012 at 11:50 PM, Michael Hunger <michael...@neotechnology.com> wrote:

Marc,

the best I came up with is:

START gp=node(6) MATCH gp-[:B]->c<-[:B]-mp<-[:SW|G]-u with mp, collect(u) as us where NONE(n in us where n.name ='u1') return mp

http://tinyurl.com/7x8t3cb

This is my shot at it. There are plans to make this nicer - I'd like to skip the last part of the match (mp-[?]-p) and move that entirely to the WHERE, but not yet.

START gw1=node(6) 

MATCH gw1-[:B]->c<-[:B]-mp-[?:B]-p 

WHERE p is null or p.name!="u1" 

RETURN mp

http://tinyurl.com/d9mayxf

HTH,

Andrés

[Marc de Verdelhan]

Andrés,

It seems you misunderstood what I'd like to do. I don't want to keep p1 but to remove it. Michael's solution works on this little graph. I'll test it on a bigger one tomorrow. However there should be a more elegant way to do this.

BTW you're right: moving the last part of the MATCH clause to the WHERE would be nicer.

Thank you guys.

Marc

[Marc de Verdelhan]

Just for saying I found simpler: start gp=node(6) match gp-[:B]->c<-[:B]-mp<-[:SW|G]-u with mp, collect(u.name) as uns where not('u1' in uns) return mp
Works well.

Cheers,

Marc

[Peter Neubauer]

Cool,
thanks for sharing Marc!

Cheers,

/peter neubauer

G:  neubauer.peter
S:  peter.neubauer
P:  +46 704 106975
L:   http://www.linkedin.com/in/neubauer
T:   @peterneubauer

If you can write, you can code - @coderdojomalmo
If you can sketch, you can use a graph database - @neo4j


On Wed, May 9, 2012 at 10:12 AM, Marc de Verdelhan