Pregel | Toy single-machine implementation | Machine Learning library
kandi X-RAY | Pregel Summary
kandi X-RAY | Pregel Summary
This is a toy single-machine implementation of Pregel, Google’s system for running large-scale graph algorithms on a large cluster of machines. For an illustration of how to use this implementation of Pregel, see the example code in pagerank.py. For more information, see
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Top functions reviewed by kandi - BETA
- Run the loop
- Starts the superstep
- Return a partition of vertices
- Distribute incoming messages
- Check if all vertices are active
- Return the worker number for a given vertex
- Run the step
- Update all vertices
Pregel Key Features
Pregel Examples and Code Snippets
Community Discussions
Trending Discussions on Pregel
QUESTION
The following code runs well, it print out the shortest path length between two vertexes. But how can I print out the real path or the detail edges (not only the length) between two vertexes?
...ANSWER
Answered 2021-Nov-11 at 05:08You can use graphFrame.
QUESTION
I have wrote my algorithm with Pregel in Spark GraphX. But unfortunately I get TypeMismatch Error.
I load the graph with : val my_graph= GraphLoader.edgeListFile(sc, path). So the beginning the nodes have a structure such as:
ANSWER
Answered 2020-Aug-14 at 06:12The main problem is that you use two different types for the messages. The initial messages are of type mutable.HashMap[VertexId, (Double,VertexId)] but after merging two (with the mergeMessage function) the type becomes mutable.HashMap[VertexId, List[(Double,VertexId)]]. The problem here is that now the merged message can't merge with another message since the type is wrong.
There are two ways to solve this:
- Change the message type to
mutable.HashMap[VertexId, List[(Double,VertexId)]], making sure the initial messages matches this. - Keep the message type as
mutable.HashMap[VertexId, (Double,VertexId)]and change the output type ofmergeMessageto match.
Below are some sketches on possible solutions for both options. There could be some errors inside them since the actual wanted logic is not very clear (there are some unused variables in the code, etc.) Both options can run when combined with the rest of the code and will return a new graph.
Solution 1:
You need to adjust sendMessage, mergeMessage and initialMessage to handle Lists. This could be done as follows:
QUESTION
I am trying to define sendMessage function in Pregel in GraphX to send each nodes attribute to its neighbors.
the graph has a structure such as:
ANSWER
Answered 2020-Aug-03 at 11:35The problem is here: you have a graph that its nodes property is (VertexId,Double) but you have defined the e: EdgeTriplet[VertexId, ED] which needs to be corrected and it should be e: EdgeTriplet[(VertexId,Double), ED]. This means that your vertexes or your nodes property in Graph have (VertexId,Double)as their property.
QUESTION
I have build a property graph(60 million nodes, 40 million edges) from s3 using Apache Spark Graphx framework. I want to fire traversal queries on this graph.
My queries will be like:-
g.V().has("name","xyz").out('parent').out().has('name','abc')
g.V().has('proc_name','serv.exe').out('file_create').has('file_path',containing('Tsk04.txt')).in().in('parent').values('proc_name')
g.V().has('md5','935ca12348040410e0b2a8215180474e').values('files')
mostly queries are of form g.V().out().out().out()
Such queries are easily possible on graph db's like neo4j,titan,aws neptune since they support gremlin.
Can we traverse spark graphs in such manner. I tried spark pregel-api but its bit complex as compared to gremlin.
Reason I am looking for spark graph is because cloud solutions of above mentioned graphdbs is costly.
...ANSWER
Answered 2020-May-29 at 13:39spark graphframes library should be most convenient for you. it provides neo4j-cypher-like traversal description and use spark dataframes api for filtering
https://graphframes.github.io/graphframes/docs/_site/user-guide.html#motif-finding
Here is an example:
QUESTION
i have downloaded the Label propagation algorithm source code from internet. the source is as below:
...ANSWER
Answered 2020-Apr-02 at 06:02as i understand from your question, your label property would be Long, or Int or any other type that is different from VD. try testing this:
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No vulnerabilities reported
Install Pregel
You can use Pregel like any standard Python library. You will need to make sure that you have a development environment consisting of a Python distribution including header files, a compiler, pip, and git installed. Make sure that your pip, setuptools, and wheel are up to date. When using pip it is generally recommended to install packages in a virtual environment to avoid changes to the system.
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