i have many cubes A B C ,...
and i want to find all the common dimensions between these cubes by Mondrian
notice shared dimensions in each cube could have different names so using of
cube.getDimensions().getUniqeName()
Or
cube.getDimensions().getName()
doesn't help
What you need is to use the olap4j API. Start by getting an olap4j connection from your Mondrian instance. After that, the Schema metadata object can give you what you need if you call:
org.olap4j.Schema.getSharedDimensions()
More details on the API are available here.
Related
I'm building a web application using multiple APIs which are a part of the Microsoft cognitive Services bundle.
The API returns detected objects such as person, man, fly, kite, etc. I require a list of all possible objects that the API is capable of detecting and also the hierarchy(if available).
From the database normalization perspective, it is information that I need. Is there any documentation that I am missing out on ?
There are thousands of objects to detect, and their list is not available publicly.
That being said, the image categories are available publicly in the documentation
Computer vision can categorize an image broadly or specifically, using
the list of 86 categories in the following diagram.
If you generally need a list of objects to use then you can use publicly available object datasets including the following (arranged from oldest to newest):
COIL100
SFU
SOIL-47
ETHZ Toys
NORB
CalTech 101
PASCAL VOC
GRAZ-02
ALOI
LabelME
Tiny
CIFAR10 and CIFAR100
ImageNet
BOSS
Office
BigBIRD
MS-COCO
iLab-20M
CURE-OR
However, it is recommended to normalize your database based on the JSON you receive from the API, for example, you already know that you are going to receive objects when trying to use Detect Objects, and categories when trying to use Analyze Image, then you can work with that!
On my knowledge base deployed on Virtuoso v7.2.1, I've two RDF graphs, namely http://example.com/A and http://example.com/B, populated by triples.
I'd like to create a virtual graph http://example.com/VG that should represent the union of http://example.com/A and http://example.com/B.
Therefore, any change on either http://example.com/A and http://example.com/B should be propagated to http://example.com/VG.
Digging into the documentation I did not find pointers and the closest thing to do, the so-called RDF View, operates on tables and not RDF graphs.
Has anyone a suggestion on how to implement it? Thanks in advance
Currently, the Virtuoso way to do this is a Graph Group.
You'll need to use DB.DBA.RDF_GRAPH_GROUP_CREATE(), DB.DBA.RDF_GRAPH_GROUP_INS(), and related functions.
The Graph Group is effectively a VIEW of of a UNION of its Member Graphs, so changes to the Member Graphs are immediately reflected through the Graph Group. There is no change propagation, as such.
For future -- Virtuoso-specific questions often get faster response from on the Virtuoso users mailing list, OpenLink support forums, etc.
I've been experimenting with Titan over the past few weeks and would like some pointers on the way forward, plus a few specific questions. The purpose of the project is to store log data on a Cassandra cluster (for this question let's use the example of web traffic) and represent relationships in a Titan graph. All nodes are modelled as having an entity value and type (e.g. "google.com","hostname"), and edges have a label (e.g. "connects") as well as several attributes of the relationship (timestamp, flow length and so on).
Once this data is stored in cassandra and represented as a Titan graph, I plan to use d3 code to generate visualisations. At the end of the tunnel I am hoping to be able to build large-scale, interactive, complex graph networks that look something like this: http://goo.gl/CVEd55
My current setup is as follows:
A python script to convert log files into vertices.csv and edges.csv files for Gremlin to load in
Titan Server 0.4 (using CassandraThrift as the storage backend) - gremlin script to load converted data into Titan
Python script that uses NetworkX to open a RexPro connection, allowing the analyst to enter a custom Gremlin query, outputting the result as a JSON
Local web front-end that uses the generated JSON and d3 to display the results of the query as a graph
Ideally as a test base case, I would like the user to be able to type a Gremlin query into the web front-end and be directed to a page containing an interactive d3 graph of the result.
My specific questions are are follows:
What is the process for assigning attributes to edges? I have had trouble finding sample code that helps me represent the graph using the model listed above.
My gremlin script to load data into Titan uses bg.commit() to create a batch graph which is later referenced in the RexPro connection conn= RexProConnection('localhost,8184,'bg'). This was working originally but after changing my load script, clearing the graph in Gremlin and then reloading, the RexPro connection cannot be opened due to the graph bg apparently not existing. What is the process of updating graphs in Titan? Presumably running a load script twice using the same graph will only add nodes/vertices to the existing one, so how would I go about generating a new graph with the same name every time I update my model, and have RexPro be able to reference it when running a query?
How easy would it be to extend the interface to allow an analyst to enter SQL queries into the front end, using RexPro to access the graph in a similar way to the one described?
Apologies for the long post, but if anyone could share their expertise that would be much appreciated!
For d3 visualization, you can use force directed graph. There are a few variations of them.
Relationship Graph
https://vida.io/documents/qZ5SJdRJfj3XmSXYJ
Force Layout Tree
https://vida.io/documents/sy7vzWW7BJEvKdZeL
If your network contains a large number of node and edges, you'll need to cluster data before visualizing. You can use tools like Gephi, NodeXL to perform clustering. Then use clustered data to build force directed visualization.
What is the process for assigning attributes to edges?
The process is the same as adding properties to vertices. Get an Edge instance then do:
Edge e = g.addEdge(v1,v2,'label')
e.setProperty('weight',0.1d)
As for:
What is the process of updating graphs in Titan? Presumably running a load script twice using the same graph will only add nodes/vertices to the existing one, so how would I go about generating a new graph with the same name every time I update my model, and have RexPro be able to reference it when running a query?
You don't want a reference to a BatchGraph after loading as it comes with limitations that will prevent you from querying. It sounds like you should just configure "yourgraph" in rexster.xml, when you load through your script, simply wrap your rexster.xml configured Graph in your code, and perform your load operations against it. When you want to query it, simply reference "yourgraph" instead of "bg".
conn = RexProConnection('localhost,8184,'yourgraph')
How easy would it be to extend the interface to allow an analyst to enter SQL queries into the front end, using RexPro to access the graph in a similar way to the one described?
It's hard to say if that's "easy" as that depends on factors outside of just the technology. I'll say that it's possible to to build an interface that accepts Gremlin queries (your wrote SQL, but I assume you meant Gremlin), passes them to Rexster and gets back an answer. What you do with that answer is up to you, but as far as Rexster's part plays into it, I don't see why that would be a problem.
As part of my academic project, I have to build a routing engine based on data supplied from OSM. I have looked at the data model of OSM and I'm all fine with it. However, I'm having trouble converting an OSM XML file into a graph structure (nodes and edges) that I can use to apply search algorithms (Dijkstra, A* etc.) on. I would like the graph to be stored in memory to allow fast read/write.
So can anyone shed light or suggest techniques on how this can be done, or even provide pointers for further research.
Please note that I'm not allowed to re-use existing routing engines as this would defeat the purpose of doing the project.
All you need to do is:
create a node for every <node> item
every <way> entry is a sequenced list of <nd> items, each of which is a backreference to a node. So for each <way>, you iterate pairwise through its <nd>s and create an arc between the two nodes referenced.
You can do this in one pass using a streaming XML parser, since the XML data defines all the nodes before the ways.
The data doesn't intrinsically include distances, so you need to calculate that from the latlon of each node. You should also take account of the road type (highway=*) and the access info (access=*) in your routing, and you probably also want to ignore ways that are not traversable (eg waterway=stream) but that's all down to your specific situation.
http://wiki.openstreetmap.org/wiki/Elements
I have an application that stores relationship information in a MySQL table (contact_id, other_contact_id, strength, recorded_at). This is fine if all I need to do is show who a contact's relationships are or even to generate a list of mutual contacts for two contacts.
But now I need to generate stats like: 'what was the total number of 2-way connections of strength 3 or better in January 2011' or (assuming that each contact is part of a group) 'which group has the most number of connections to other groups' etc.
I quickly found that the SQL for generating these stats became unwieldy real fast.
So I wrote a script that for any given date it will generate a graph in memory. I could then run whatever stat I wanted against that graph. Much easier to understand and in general, much more performant also -- except for the generating the graph part.
My next thought was to cache those graphs so I could call on them whenever I needed to run a new stat (or generate a later graph: eg for today's graph I take yesterday's graph and apply any changes that happened since yesterday). I tried memcached which worked great until the graphs grew > 1 MB.
So now I'm thinking about using a graph database like Neo4J.
Only problem is, I don't have just one graph. Or I do, but it is one that changes over time and I need to be able to query it with different reference times.
So, can I:
store multiple graphs in Neo4J and rertrieve/interact with them separately? i would then create and store separate social graphs for each date.
or
add valid to and from timestamps to each edge and filter the graph appropriately: so if i wanted a graph for "May 1st" i would only follow the newest edge between two noeds that was created before "May 1st" (and if all the edges were created after May 1st then those nodes wouldn't be connected).
I'm pretty new to graph databases so any help/pointers/hints will be appreciated.
Right now you can store just one graph database in a single Neo4j instance, but this one graphdb can contain as many different sub-graphs as you like. You only have to keep that in mind when doing global operations (like index queries) but there you can do compound queries that include timestamped properties as well to limit the results.
One way of doing that is, as you said adding temporal information to edges to represent the structure of a graph for a given date you can then traverse the structure of the graph back then.
Reference node has a different meaning in Neo4j.
Using category nodes per day (and linking them and also aggregating them for higher level timespans) is the more graphy way of categorizing nodes than indexed properties. (Effectively these are in-graph indices that you can easily include in your traversals and graph queries).
You don't have to duplicate the nodes as long as you are only interested in different temporal structures. If your nodes are also different (e.g. changing properties, you could either duplicate them, and so effectively creating different subgraphs) or create a connected list of history nodes on each node that contain just the changes (or the full snapshot depending on your requirements).
Your domain sounds very fitting for the graph database. If you have more and detailed questions feel free to join the Neo4j mailing list.
Not the easiest solution (I'm assuming you only work with one machine), but if you really want to separate your graphs, you only need to remember that a graph is a directory.
You can then create a dynamic loader class which takes the path of the database you want, load it in memory for the query, and close it after you getting your answer. You could also configure a proxy server, and send 2 parameters to your loader: your query (which I presume is a cypher query in this case) and the path of the database you want to query.
This is not adequate if you have tons of real-time queries to answer. But if it is simply for storing and doing some analytics over data sets, it can definitly answer your needs.
This is an old question, but starting with Neo4j 4.x, multi-tenancy is supported and you can have different databases within the same Neo4j server (with distinct RBAC permissions).