Please, how can i get the list of nodes in pastry overlay ? is that possible ?
Thank you.
I don't believe its straight forward to get a list of all the nodes in a pastry overlay. Not all nodes are aware of every node in the overlay. However they do know about the nodes in their leafset. The leafset can be found using : node.getLeafSet()
I've done queit a bit of reading on pastry and generally there doesn't seem to be a need to check all the nodes in a network. If you want to see this for testing purposes i.e that a node has enetered the overlay successfully, just use the .getLeafSet()
Related
I'm have a large network of ~300K nodes that my machine has a hard time plotting with Cytpscape (Desktop version under Windows).
I know that the network has discrete groups that are not interconnected - I also have the id of those groups as a node attribute.
I want to be able to graph each group based on what id I select.
I tried achieving this with the filter (Cytoscape gave me the option to not plot the graph when opening it the first time - "Do you want to create a view for your large network now?") but it still seems to try to plot the entire graph when setting the filter and then clicking on "Create View".
So in short: Is there any way to "pre-filter" the graph, or to somehow else cut it up so that cytoscape will plot the one I want?
Any thoughts would be appreciated.
You are almost there. Once you have the filter set, then you need to create a subnetwork (see File > New Network), then you can create a view of that subset (or it will automatically be created if the node count is below the threshold).
I am completely new to NEO4j and using it for the first time ever now for my masters program. Ive read the documentation and watched tutorials online but can’t seem to figure out how I can represent my nodes in the way I want.
I have a dataframe with 3 columns, the first represents a page name, the second also represents a page name, and the third represents a similarity score between those two pages. How can I create a graph in NEO4J where the nodes are my unique page names and the relationships between nodes are drawn if there is a similarity score between them (so if the sim-score is 0 they don’t draw a relationship)? I want to show the similarity score as the text of the relationship.
Furthermore, I want to know if there is an easy way to figure out which node had the most relationships to other nodes?
I’ve added a screenshot of the header of my DF for clarity https://imgur.com/a/pg0knh6. I hope anyone can help me, thanks in advance!
Edit: What I have tried
LOAD CSV WITH HEADERS FROM 'file:///wiki-small.csv' AS line
MERGE (p:Page {name: line.First})
MERGE (p2:Page {name: line.Second})
MERGE (p)-[r:SIMILAR]->(p2)
ON CREATE SET r.similarity = toFloat(line.Sim)
Next block to remove the similarities relationships which are 0
MATCH ()-[r:SIMILAR]->() WHERE r.Sim=0
DELETE r
This works partially. As in it gives me the correct structure of the nodes but doesn't give me the similarity scores as relationship labels. I also still need to figure out how I can find the node with the most connections.
For the first question:
How can I create a graph in NEO4J where the nodes are my unique page names and the relationships between nodes are drawn if there is a similarity score between them (so if the sim-score is 0 they don’t draw a relationship)?
I think a better approach is to remove in advance the rows with similarity = 0.0 before ingesting them into Neo4j. Could it be something feasible? If your dataset is not so big, I think it is very fast to do in Python. Otherwise the solution you provide of deleting after inserting the data is an option.
In case of a big dataset, maybe it's better if you load the data using apoc.periodic.iterate or USING PERIODIC COMMIT.
Second question
I want to know if there is an easy way to figure out which node had the most relationships to other nodes?
This is an easy query. Again, you can do it with play Cypher or using APOC library:
# Plain Cypher
MATCH (n:Page)-[r:SIMILAR]->()
RETURN n.name, count(*) as cat
ORDER BY cnt DESC
# APOC
MATCH (n:Page)
RETURN apoc.node.degree(n, "SIMILAR>") AS output;
EDIT
To display the similarity scores, in Neo4j Desktop or in the others web interfaces, you can simply: click on a SIMILARITY arrow --> on the top of the running cell the labels are shown, click on the SIMILAR label marker --> on the bottom of the running cell, at the right of Caption, select the property that you want to show (similarity in your case)
Then all the arrows are displayed with the similarity score
To the second question: I think you should keep a clear separation between the way you store data and the way you visualize it. Having the similarity score (a property of the SIMILARITY edge) as a "label" is something that is best dealt with by using an adequate viz library or platform. Ours (Graphileon) could be such a platform, although there are also others.
We offer the possibility to "style" the edges with so-called selectors like
"label":"(%).property.simScore" that would use the simScore as a label. On top of that you could do thing like
"width":"evaluate((%).properties.simScore < 0.500 ? 3 : 10)"
or
"fillColor":"evaluate((%).properties.simScore < 0.500 ? grey : red)"
to distinguish visually high simScores.
Full disclosure : I work for Graphileon.
I am trying to learn neo4j, so I just took a use case of a travel app to learn but I am not sure about the optimal way to solve it. Any help will be appreciated.
Thanks in advance.
So consider a use case in which I have to travel from one place (PLACE A) to other (PLACE C) by train, but there is no direct connection between the two places. And so we have to change our train in PLACE B.
Two places are connected via a relation IS_CONNECTED relation. refering to green nodes in the image
And then if there is an is_connected relation between two place then there will be an out going relation i.e. CONNECTED_VIA to a common train from both the node which implies how they are connected referring to red nodes in image
my question is how are we suppose to know that we have to change the station from place b
My understanding is:
We will check where the two places are connected via IS_CONNECTED relationship
match (start:place{name:"heidelberg"}), (end:place{name:"frankfurt"})
MATCH path = (start)-[:IS_CONNECTED*..]->(end)
RETURN path
this will show that these two places are connected
Then we will see that if place A and place c are directly connected or not by the query
match (p:place{name:"heidelberg"})-[:CONNECTED_VIA]->(q)<-[:CONNECTED_VIA]-(t:place{name:"frankfurt"})
return q
And this will return nothing because there is no direct connections
My brain stopped functioning after this. I am trying to figure how from past 3 days. I am sorry I look ao confused
Please click here for the image of what i am referring
You'll want to use variable-length relationships in your :CONNECTED_VIA match, and then get the :Place nodes that are in your path. And it's usually a good idea to use an upper bound, whatever makes sense in your graph.
Then we can use a filter on the nodes in your path to only keep the ones that are :Place nodes.
match path = (p:place{name:"heidelberg"})-[:CONNECTED_VIA*..4]-(t:place{name:"frankfurt"})
return path, [node in nodes(path)[1..-1] where node:Place] as connectionPlaces
And if you're only interested in the shortest paths, you may want to check the shortestPath() or shortestPaths() functions.
One last thing to note...when determining if two locations are connected, if all you need is a true or false if they're connected, you can use the EXISTS() function to return whether such a pattern exists:
match (start:place{name:"heidelberg"}), (end:place{name:"frankfurt"})
return exists((start)-[:IS_CONNECTED*..5]->(end))
I am trying to use Gephi to help graph interview analysis results. The relationship map is only used to describe conventional connections and life cycles. What I would like to do is to size the nodes based on the number of interview responses that talk about the node, not the number of connections it has or the weighting of those connections. Can Gephi do this and if so, how do I do it please?
I have loaded in node weightings and can see this as part of node labels, but haven't been able to find a way of this having an effect on node size.
Many thanks
Data input field - change input format to integer
You can load the graph in gexf format adding a float attribute and add this attribute to ALL the nodes. It would like something like:
```
...
...
```
Once imported in Gephi, just go to the appearance tab and it will appear as one more attribute in "ranking" drop-down list.
If any problem with gefx format, let me know and I'll will share a whole example (just trying to remain short :-)
Regards
I used spatial features of Neo4j. I faced following problem in that. I used Node API to create a node and add that node to Spatial Layer.
Que 1 :- In Neo4j Browser client when i retrive all node it shows me two node with same node no. (One is real node and other is added to spatial layer). I think second node is for indexing purpose. Need clerification on this. I am wrong or it's bug or it's normal behaviour.
Que 2 :- If I update latitude and longitude of real node then second node in spatial layer is not updated with new value of co-ordinates. How can i update both node?
Any Help will be very helpful for me.
Thanks.
Neo4j spatial adds a second node within the geo R-Tree that represents the location of your domain node.
You have to remove it from the index and re-add it again.
As #Michael pointed correctly, it's a normal behavior as it's a representation of location of your node.
To remove a node from an index, you can delete the node, using "internal" id of the indexed node. Please check my answer here, for the detailed steps on how to do that. After that you can easily re-add the node to index.