I've been playing with neo4j for a geneology site and it's worked great!
I've run into a snag where finding the starting node isn't as easy. Looking through the docs and the posts online I haven't seen anything that hints at this so maybe it isn't possible.
What I would like to do is pass in a list of genders and from that list follow a specific path through the nodes to get a single node.
in context of the family:
I want to get my mother's father's mother's mother. so I have my id so I would start there and traverse four nodes from mine.
so pseudo query would be
select person (follow childof relationship)
where starting node is me
where firstNode.gender == female
AND secondNode.gender == male
AND thirdNode.gender == female
AND fourthNode.gender == female
Focusing on the general solution:
MATCH p = (me:Person)-[:IS_CHILD_OF*]->(ancestor:Person)
WHERE me.uuid = {uuid}
AND length(p) = size({genders})
AND extract(x in tail(nodes(p)) | x.gender) = {genders}
RETURN ancestor
here's how it works:
match the starting node by id
match all the variable-length paths going to any ancestor
constrain the length of the path (i.e. the number of relationships, which is the same as the number of ancestors), as you can't parameterize the length in the query
extract the genders in the path
nodes(p) returns all the nodes in the path, including the starting node
tail(nodes(p)) skips the first element of the list, i.e. the starting node, so now we only have the ancestors
extract() extracts the genders of all the ancestor nodes, i.e. it transforms the list of ancestor nodes into their genders
the extracted list of genders can be compared to the parameter
if the path matched, we can return the bound ancestor, which is the end of the path
However, I don't think it will be faster than the explicit solution, though the performance could remain comparable. On my small test data (just 5 nodes), the general solution does 26 DB accesses whereas the specific solution only does 22, as reported by PROFILE. Further profiling would be needed on a larger database to compare the performances:
PROFILE MATCH p = (me:Person)-[:IS_CHILD_OF*]->(ancestor:Person)
WHERE me.uuid = {uuid}
AND length(p) = size({genders})
AND extract(x in tail(nodes(p)) | x.gender) = {genders}
RETURN ancestor
The general solution has the advantage of being a single query which won't need to be parsed again by the Cypher engine, whereas each generated query will need to be parsed.
It was more simple than I thought. Maybe there is still a better way so I'll leave this open for a bit.
the query would be
MATCH (n1:Person { Id: 'f59c40de-506d-4829-a765-7a3ae94af8d1' })
<-[:CHILDOF]-(n2 { Gender:'0'})
<-[:CHILDOF]-(n3 { Gender:'1'})
<-[:CHILDOF]-(n4 { Gender:'1'})
RETURN n4
and for each generation back would add a new row.
The equivalent query would look something like this:
MATCH (me:Person)
WHERE me.ID = ?
WITH me
MATCH (me)-[r:childof*4]->(ancestor:Person)
WITH ancestor, EXTRACT(rel IN r | endNode(rel).gender) AS genders
WHERE genders = ?
RETURN ancestor
Disclaimer, I haven't double-checked the syntax.
In Neo4j you typically find your start node first, typically by an ID of some sort (modify as required to match on a unique property). We then traverse a number of relationships to an ancestor, extract the gender property of all end nodes in the traversed relationships, and compare the genders to the expected list of genders (you'll need to make sure the argument is a bracketed list in the desired order).
Note that this approach filters down all possible results with that degree of childof relationship as opposed to walking your graph, so higher degrees of relationship (the higher the degree of ancestry you're querying), the slower the call will get.
I'm also unsure if you can parameterize the degree of the variable relationship, so that might prevent this from being a generalized solution for any degree of ancestry.
I'm not sure if you want a generic query which can work whatever the collection of genders you pass, or a specific solution.
Here's the specific solution: you match the path with the wanted length, and match each gender, as you've already noted in your own answer.
MATCH (me:Person)-[:IS_CHILD_OF]->(p1:Person)
-[:IS_CHILD_OF]->(p2:Person)
-[:IS_CHILD_OF]->(p3:Person)
-[:IS_CHILD_OF]->(p4:Person)
WHERE me.uuid = {uuid}
AND p1.gender = {genders}[0]
AND p2.gender = {genders}[1]
AND p3.gender = {genders}[2]
AND p4.gender = {genders}[3]
RETURN p4
Now, if you want to pass in a list of genders of an arbitrary length, it's actually possible. You match a variable-length path, make sure it has the right length (matching the number of genders), then match each gender in sequence.
MATCH p = (me:Person)-[:IS_CHILD_OF*]->(ancestor:Person)
WHERE me.uuid = {uuid}
AND length(p) = size({genders})
AND all(i IN range(0, size({genders}) - 1)
WHERE {genders}[i] = extract(x in tail(nodes(p)) | x.gender)[i])
RETURN ancestor
Building on #InverseFalcon's answer, you can actually compare collections, which simplifies the query:
MATCH p = (me:Person)-[:IS_CHILD_OF*]->(ancestor:Person)
WHERE me.uuid = {uuid}
AND length(p) = size({genders})
AND extract(x in tail(nodes(p)) | x.gender) = {genders}
RETURN ancestor
Related
I have for example the following graph in Neo4j
(startnode)-[:BELONG_TO]-(Interface)-[:IS_CONNECTED]-(Interface)-[:BELONG_TO]-
#the line below can repeat itself 0..n times
(node)-[:BELONG_TO]-(Interface)-[:IS_CONNECTED]-(Interface)-[:BELONG_TO]-
#up to the endnode
(endnode)
There is an Interface properties I also need to match on. I do not want to follow all the paths, I just the one with Interface Node property I am looking for. For example Interface.VlanList CONTAINS ",23,"
I have done the following in Cypher but it applies that I already know how many iterations I am going to find which in reality is not the case.
match (n:StartNode {name:"device name"}) -[:BELONG_TO]- (i:Interface) -[:IS_CONNECTED]- (ii:Interface)-[:BELONG_TO]-(nn:Node) -[:BELONG_TO]- (iii:Interface) -[:IS_CONNECTED]- (iiii:Interface) -[:BELONG_TO]-(nnn:Node)
where i.VlanList CONTAINS ",841,"
AND ii.VlanList CONTAINS ",841,"
AND iii.VlanList CONTAINS ",841,"
return n, i,ii,nn,iii,iiii,nnn
I have been looking at the documentation but can not work out how the above could be resolved.
This should work:
// put the searchstring in a variable
WITH ',841,' AS searchstring
// look up start end endnode
MATCH (startNode: .... {...}), (endNode: .... {...})
// look for paths of variable length
// that have your search string in all nodes,
// except the first and the last one
WITH searchstring,startNode,endNode
MATCH path=(startnode)-[:BELONG_TO|IS_CONNECTED*]-(endnode)
WHERE ALL(i IN nodes(path)[1..-1] WHERE i.VlanList CONTAINS searchstring)
RETURN path
You can also look at https://neo4j.com/labs/apoc/4.1/graph-querying/path-expander/ for more ideas about how you can limit the pathfinding.
This query should work for you (assuming that the relationship directions I chose are correct):
MATCH p = (sNode:StartNode)-[:BELONG_TO]->(i1:Interface)-[:IS_CONNECTED]->(i2:Interface)-[:BELONG_TO]->(n1)-[:BELONG_TO|IS_CONNECTED*0..]->(eNode:Node)
WHERE sNode.name = "device name" AND eNode.name = "foo" AND LENGTH(p)%3 = 0
WITH p, i1, i2, n1, eNode, RELATIONSHIPS(p) AS rels, NODES(p) AS ns
WHERE n1 = eNode OR (
ALL(j IN RANGE(3, SIZE(rels)-3, 3) WHERE
'BELONG_TO' = TYPE(rels[j]) = TYPE(rels[j+2]) AND
'IS_CONNECTED' = TYPE(rels[j+1])) AND
ALL(x IN ([i1, i2] + REDUCE(s = [], i IN RANGE(3, SIZE(ns)-2, 3) | CASE WHEN i%3 = 0 THEN s ELSE s +ns[i] END))
WHERE x:Interface AND x.VlanList CONTAINS $substring)
)
RETURN p
It checks that the returned paths have the required pattern of node labels, node property value, and relationship types. It takes advantage of the variable length relationship syntax, using zero as the lower bound. Since there is no upper bound, the variable length relationship query query can take "forever" to finish (and in such a situation, you should use a reasonable upper bound).
I have this graph:
A-[:X]->B-> a whole tree of badness
A-[:Y]->C-> a whole tree of goodness
I would like to know how to specify a path starting with A that excludes the :X relationship.
In this case "Y" could be any one of a number of different edge types. I do not want to specify them explicitly.
How do I write a path statement that includes A-[*]-B where * is not :X but can be anything else?
Solution for a fixed number of relationships between A and B
You can exclude a relationship type by matching all relationships from A to B and then filter out a specific type with WHERE NOT
MATCH p = (a:Label1)-[]-(b:Label2)
WHERE NOT (a)-[:X]-(b)
RETURN p
Solution for a variable length path between A and B
If you have a variable length path between A and B you cannot put the exact pattern in the WHERE NOT. Instead, you can use a NONE predicate on the path:
MATCH p = (a:Label1)-[*]-(b:Label2)
// this WHERE makes sure that none of the relationships in the
// returned path fulfill the criterion type(relationship) = 'X'
WHERE NONE (r in relationships(p) WHERE type(r) = 'X')
RETURN p
This Cypher query is simpler than the variable-length path query from #MartinPreusse, as it avoids using the RELATIONSHIPS function. Profiling shows that its execution plan is also a bit simpler, so it might be faster.
MATCH p=(a:Label1)-[rels*]-(b:Label2)
WHERE NONE (r IN rels WHERE type(r)= 'X')
RETURN p
I am attempting to query an ontology of health represented as an acyclic, directed graph in Neo4j v2.1.5. The database consists of 2 million nodes and 5 million edges/relationships. The following query identifies all nodes subsumed by a disease concept and caused by a particular bacteria or any of the bacteria subtypes as follows:
MATCH p = (a:ObjectConcept{disease}) <-[:ISA*]- (b:ObjectConcept),
q=(c:ObjectConcept{bacteria})<-[:ISA*]-(d:ObjectConcept)
WHERE NOT (b)-->()--(c) AND NOT (b)-->()-->(d)
RETURN distinct b.sctid, b.FSN
This query runs in < 1 second and returns the correct answers. However, adding one additional parameter adds substantial time (20 minutes). Example:
MATCH p = (a:ObjectConcept{disease}) <-[:ISA*]- (b:ObjectConcept),
q=(c:ObjectConcept{bacteria})<-[:ISA*]-(d:ObjectConcept),
t=(e:ObjectConcept{bacteria})<-[:ISA*]-(f:ObjectConcept),
WHERE NOT (b)-->()--(c)
AND NOT (b)-->()-->(d)
AND NOT (b)-->()-->(e)
AND NOT (b)-->()-->(f)
RETURN distinct b.sctid, b.FSN
I am new to cypher coding, but I have to imagine there is a better way to write this query to be more efficient. How would Collections improve this?
Thanks
I already answered that on the google group:
Hi Scott,
I presume you created indexes or constraints for :ObjectConcept(name) ?
I am working with an acyclic, directed graph (an ontology) that models
human health and am needing to identify certain diseases (example:
Pneumonia) that are infectious but NOT caused by certain bacteria
(staph or streptococcus). All concepts are Nodes defined as
ObjectConcepts. ObjectConcepts are connected by relationships such as
[ISA], [Pathological_process], [Causative_agent], etc.
The query requires:
a) Identification of all concepts subsumed by the concept Pneumonia as follows:
MATCH p = (a:ObjectConcept{Pneumonia}) <-[:ISA*]- (b:ObjectConcept)
this already returns a number of paths, potentially millions, can you check that with
MATCH p = (a:ObjectConcept{Pneumonia}) <-[:ISA*]- (b:ObjectConcept) return count(*)
b) Identification of all concepts subsumed by Genus Staph and Genus Strep (including the concept Genus Staph and Genus Strep) as follows. Note:
with b MATCH (b) q = (c:ObjectConcept{Strep})<-[:ISA*]-(d:ObjectConcept), h = (e:ObjectConcept{Staph})<-[:ISA*]-(f:ObjectConcept)
this is then the cross product of the paths from "p", "q" and "h", e.g. if all 3 of them return 1000 paths, you're at 1bn paths !!
c) Identify all nodes(p) that do not have a causative agent of Strep (i.e., nodes(q)) or Staph (nodes(h)) as follows:
with b,c,d,e,f MATCH (b),(c),(d),(e),(f) WHERE (b)--()-->(c) OR (b)-->()-->(d) OR (b)-->()-->(e) OR (b)-->()-->(f) RETURN distinct b.Name;
you don't need the WITH or even the MATCH (b),(c),(d),(e),(f)
what connections are there between b and the other nodes ? do you have concrete ones? for the first there is also missing one direction.
the where clause can be a problem, in general you want to show that perhaps this query is better reproduced by a UNION of simpler matches
e.g
MATCH (a:ObjectConcept{Pneumonia}) <-[:ISA*]- (b:ObjectConcept)-->()-->(c:ObjectConcept{name:Strep}) RETURN b.name
UNION
MATCH (a:ObjectConcept{Pneumonia}) <-[:ISA*]- (b:ObjectConcept)-->()-->(e:ObjectConcept{name:Staph}) RETURN b.name
UNION
MATCH (a:ObjectConcept{Pneumonia}) <-[:ISA*]- (b:ObjectConcept)-->()-->(d:ObjectConcept)-[:ISA*]->(c:ObjectConcept{name:Strep}) return b.name
UNION
MATCH (a:ObjectConcept{Pneumonia}) <-[:ISA*]- (b:ObjectConcept)-->()-->(d:ObjectConcept)-[:ISA*]->(c:ObjectConcept{name:Staph}) return b.name
another option would be to utilize the shortestPath() function to find one or all shortest path(s) between Pneumonia and the bacteria with certain rel-types and direction.
Perhaps you can share the dataset and the expected result.
The query was successfully accomplished using UNION functions as follows:
MATCH p = (a:ObjectConcept{sctid:233604007}) <-[:ISA*]- (b:ObjectConcept),
q = (c:ObjectConcept{sctid:58800005})<-[:ISA*]-(d:ObjectConcept)
WHERE NOT (b)-->()--(c) AND NOT (b)-->()-->(d)
RETURN distinct b
UNION
MATCH p = (a:ObjectConcept{sctid:233604007}) <-[:ISA*]- (b:ObjectConcept),
t = (e:ObjectConcept{sctid:65119002}) <-[:ISA*]- (f:ObjectConcept)
WHERE NOT (b)-->()-->(e) AND NOT (b)-->()-->(f)
RETURN distinct b
The query runs in sub 20 seconds vs. 20 minutes by reducing the cardinality of the objects being queried.
I'm new to neo4j and am trying to map the longest path to a known node. In this example there is only a single, straight path. (For example, node1 => node2 => node3 => node4 => node5 => node6). How can I write that query?
A complication is to limit only relationships and with a certain property. For example, all the relationships are types :KNOWS, but then there is an attribute on it of "signal", and I want to run the query only for relationships r:KNOWS where r.signal = 10.
Below is what works to get the last two nodes in the path:
MATCH (end)<-[r:knows]-(node)
WHERE r.signal = 10
AND end.name = 4
RETURN node.name, end.name, r.signal
Here is my next attempt using the * to get all lengths, and a combination of filter and extract to handle the collection:
MATCH (end)<-[r:knows*]-(node)
WHERE end.name = 4
WITH end, node, [x IN r WHERE x.signal = 10 | x.signal] as signals
RETURN node.name, end.name, signals
But it's still not quite right since it returns all iterations, and only the pairs. I'd like to find the longest path, and return an array of all the node names (not just a pair at a time). Any pointers on how to approach this are much appreciated, or helpful links to tutorials. I've already done the neo4j online training.
Here's a way to get a maximum length/longest path:
MATCH p=(end {name: 4})<-[r:knows*]-(node)
WITH max(length(p)) as longestPathLength
MATCH p2=(end {name: 4})<-[r:knows*]-(node)
WITH [x IN nodes(p2) | x.signal] as signals,
p2 as p2,
longestPathLength as longestPathLength
WHERE length(p2) = longestPathLength
RETURN p2, signals;
First, you need to be matching the path and assigning it to a variable, here p and p2. You can extract the node names by using the collection function as you were, across nodes(p2). Finally, to find the longest path length, just find all of them, and select the path with the maximum length. Then go back and extract only node names from paths that happen to have that length.
This probably isn't the most efficient way to do it, but it looks like it works.
I'm new to cypher, neo4j and graph databases in general. The data model I was given to work with is a tad confusing, but it looks like the nodes are just GUID placeholders with all the real "data" as properties on relationships to the nodes (which relates each node back to node zero).
Each node (which basically only has a guid) has a dozen relations with key/value pairs that are the actual data I need. (I'm guessing this was done for versioning?.. )
I need to be able to make a single cypher call to get properties off two (or more) relationships connected to the same node -- here is two calls that I'd like to make into one call;
start n = Node(*)
match n-[ar]->m
where has(ar.value) and has(ar.proptype) and ar.proptype = 'ccid'
return ar.value
and
start n = Node(*)
match n-[br]->m
where has(br.value) and has(br.proptype) and br.proptype = 'description'
return br.value
How do I go about doing this in a single cypher call?
EDIT - for clarification;
I want to get the results as a list of rows with a column for each value requested.
Something returned like;
n.id as Node, ar.value as CCID, br.value as Description
Correct me if I'm wrong, but I believe you can just do this:
start n = Node(*)
match n-[r]->m
where has(r.value) and has(r.proptype) and (r.proptype = 'ccid' or r.proptype = 'description')
return r.value
See here for more documentation on Cypher operations.
Based on your edits I'm guessing that you're actually looking to find cases where a node has both a ccid and a description? The question is vague, but I think this is what you're looking for.
start n = Node(*)
match n-[ar]->m, n-[br]->m
where (has(ar.value) and has(ar.proptype) and ar.proptype = 'ccid') and
(has(br.value) and has(br.prototype) and br.proptype = 'description')
return n.id as Node, ar.value as CCID, br.value as Description
You can match relationships from two sides:
start n = Node(*)
match m<-[br]-n-[ar]->m
where has(ar.value) and has(ar.proptype) and ar.proptype = 'ccid' and
has(br.value) and has(br.proptype) and br.proptype = 'description'
return ar.value, br.value