New to Neo4j. My goal is to make a database with various csv sources. I have created node labels of "geochemistry" and "geospatial" to be linked with the "LABID" node via a common property. I have loaded in one dataset easily, and made the necessary connections with the ":LOCATED" relationship being defined as between the geospatial and LABID nodes.
However, moving on to the second csv source, I am a little confused. I have tried matching the new geospatial data (which have no current relationships) to another set of Lab IDs. Below is my current code:
MATCH (g:geospatial) WHERE NOT (g)-[:LOCATED]->(:LABID)
MATCH (l:LABID)
WHERE l.labid = g.Sample_ID
MERGE (g)-[r:LOCATED]->(l)
RETURN r
labid is a current property in LABID, and so is Sample_ID to the geospatial nodes.
After completing the above query, the output is "(no changes, no records)"
Thanks for the help in advance!
Related
I am trying to use neo to create a unified data dictionary across many datasets, since many of the columns are shared. I have one dictionary as a csv per dataset, with common columns in each. I am new to graph databases, but I think the pseudo code should look like this:
Create dataset node (single node with name and featues of dataset)
Upload data dictionary for dataset in step 1
If field node exists, create relationship between dataset node and existing field node.
If not exists, create field node and relationship between dataset node and field node.
Excluding step 1 which I am doing manually for each dataset node, here is what I have so far:
USING PERIODIC COMMIT LOAD CSV WITH HEADERS FROM "file:.csv" AS csvLine
MERGE (d:data {field: csvLine.Field, dtype: csvLine.Type, format: csvLine.Format})
ON CREATE SET d.field = csvLine.Field
ON MATCH SET d.field = csvLine.Field
CREATE (dataset)-[r:CONTAINS]->(d);
The results appear almost correct, only new fields are created, and the number of created relationships is equal to the number of fields in the uploaded dataset. However, the (dataset) node I created previously does not connect to the fields. Instead, label-less nodes are created and attach to all the fields in the new dataset. How can I properly connect the dataset node to the appropriate fields?
The problem is here: CREATE (dataset)-[r:CONTAINS]->(d)
dataset is a variable, and this the first time it's used in the query, so this CREATE will create a blank node, bind it to the dataset variable, then create the relationship to d.
Variables only last for the duration of a query (or less, if they are not carried in scope with the WITH clause), and are never persisted to the database. If you previously created some node in a different query with the dataset variable, then that variable went out of scope when the query ended. If you want to refer to that same node again, you will need to match to that node in this query.
I'm building a Neo4J system just do to visualization in the Neo4J browser. I build the various nodes and relationships and I can visualize the database by running match (n) return n. The problem is that the resulting display shows the relationship names but not their associated properties. Can anyone tell me the cypher query to show the entire database including relationship properties? Thanks.
The neo4j browser does not support visualizing all properties (for nodes or relationships) at the same time. Such a capability would generally result in a very congested and unusable visualization, especially since the browser would also have to display the property names.
You can, however, opt to show the value of a single property per node label or or relationship type as its caption. You can do that manually, or you can edit the GRASS file to set all of the captions at once. As an example of how to set relationship captions in the GRASS file, the following entry in that file would specify that all BAR relationships should show their foo property:
relationship.BAR {
caption: '{foo}';
}
Im using neo4j to store information about maps and sensors. Every time the map or sensor layout changes I need to keep a copy. I can imagine querying and manually creating said copy but I'm wondering if it's possible to build a neo4j type query that would do this for me.
So far all I've come up with is a way to replicate the nodes in a given label:
match ( a:some_label { some_params }) with a create ( b:some_label ) set b=a,b.other_id=value;
This would allow me to put version and time stamp info on a given snap shot.
What it doesn't do is copy the edge information. Suggestions? Maybe a second (similar) query?
If I understand you correctly, you are essentially trying to maintain a history of the state of a node and the state of its incoming relationship. One way to do this is to chain the nodes in reverse chronological order.
For example, suppose the nodes in the chain are labeled Some_label and the relationships are of type SOME_TYPE. The head node of the chain is always the current (most recent) node. Unless a Some_label node is chronologically the earliest node in the chain, it will have a SOME_TYPE relationship to the previous version of the node.
Here is how you'd insert a new relationship and node (with some properties) at the head of the chain. (Just to set up this example, I assume that the first node in the chain is linked to by some node labeled HeadRef).
MATCH (x:HeadRef)-[r1:SOME_TYPE]->(a1:Some_label)
CREATE (x)-[r2:SOME_TYPE {x: "ghi"}]->(a2:Some_label {a:123, b: true})-[r:SOME_TYPE]->(a1)
SET r=r1
WITH r1
DELETE r1
Note that this approach is also much more performant than maintaining your own other_id property to link nodes together. You should always use relationships instead -- that is the graph DB way.
I'm very new in using Neo4j and have a question regarding the computation of intersections of nodes.
Let's suppose, I have the three properties A,B,C and I want to select only the nodes that have all three properties.
I created an index for the properties and thus, I can get all nodes having one of the properties. However, afterwards I have to merge the IndexHits. Is there a way to select directly all nodes having the three properties?
My second idea was to create a node for each property and connect other nodes by relationships. I can then iterate over all relationships and get for each property a list of nodes which are connected. But again, I have to compute the intersection afterwards.
Is there a function I miss here, since I suppose it's a standard problem.
Thanks a lot,
Benny
Do you also have the values you look for? You would start with the property that limits the amount of found nodes most.
MATCH (a:Label {property1:{value1}})
WHERE a.property2 = {value2} AND a.property3 = {value3}
RETURN a
For the Java API and lucene indexes:
gdb.index().forNodes("foo").query("p1:value1 p2:value2 p3:value3")
Lucene query syntax
I am using Neo4j 1.8.2 with Neo4j Spatial 0.9 for 1.8.2 (http://m2.neo4j.org/content/repositories/releases/org/neo4j/neo4j-spatial/0.9-neo4j-1.8.2/)
Followed the example code from here http://architects.dzone.com/articles/neo4jcypher-finding-football with one change- instead of SpatialIndexProvider.SIMPLE_WKT_CONFIG, I used SpatialIndexProvider.SIMPLE_POINT_CONFIG_WKT
Everything works fine until you execute the following query:
START n=node:stadiumsLocation('withinDistance:[53.489271,-2.246704, 5.0]')
RETURN n.name, n.wkt;
n.name is null. When I explored the graph, I found this data:
Node[80]{lon:-2.20024,lat:53.483,id:79,gtype:1,bbox:-2.20024,53.483,-2.20024,53.483]}
Node[168]{lon:-2.29139,lat:53.4631,id:167,gtype:1,bbox:-2.29139,53.4631,-2.29139,53.4631]}
For Node 80 returned, it looks like this is the node created for the spatial record, which contains a property id:79. Node 79 is the actual stadium record from the example.
As per the source of IndexProviderTest, the comments
//We not longer need this as the node we get back already a 'Real' node
// Node node = db.getNodeById( (Long) spatialRecord.getProperty( "id" ) );
seem to indicate that this feature isn't available in the version I am using.
My question is, what is the recommended way to use withinDistance with other match conditions? There are a couple of other conditions to be fulfilled but I can't seem to get a handle on the actual node to actually match them.
Should I explicitly create relations? Not use Cypher and use the core API to do a traversal? Split the queries?
Two options:
a) Use GeoPipline.startNearestNeighborLatLonSearch to get a starting set of nodes, supply to subsequent Cypher query to do matching/filtering on other properties
b) Since my lat/longs are common across many entities [using centroid of an area], I can create a relation from the spatial node to all entities that are located in that area and then use one Cypher query such as:
START n=node:stadiumsLocation('withinDistance:[53.489271,-2.246704, 5.0]')
MATCH (n)<-[:LOCATED_IN]-(something)
WHERE something.someProp=5
RETURN something
As advised by Peter, went with option b.
Note though, there is no way to get the spatially indexed node back so that you can create relations from it. Had to do a withinDistance query for 0.0 distance.
can you execute the enhanced testcase I did at https://github.com/neo4j/spatial/blob/2803093d544f56d7dfe8f1d122e049fa73489d8a/src/test/java/org/neo4j/gis/spatial/IndexProviderTest.java#L199 ? It shows how to find a location, and traverse with cypher to the next node.