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https://issues.apache.org/jira/browse/FLINK-2905?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14980450#comment-14980450
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Martin Junghanns commented on FLINK-2905:
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Hi, taking your reply on the mailing list into account, I wrote three versions
of intersect now :)
(1) Intersect On Edges (join based) as you suggested on the mailing list. Does
not support duplicate edges in the input graphs.
(2) Intersect On Edges with duplicates (coGroup based). Supports duplicate
edges and outputs two edges for each matching pair in the input graphs (most
flexible imho)
(3) Intersect On Vertices. Does the same as (2), but on vertices (which should
be faster, if the vertex set is much smaller than the edge set)
Please have a look at:
https://github.com/s1ck/flink/blob/FLINK-2905/flink-libraries/flink-gelly/src/main/java/org/apache/flink/graph/Graph.java#L1482-L1652
I also wrote some test cases, I think we should be on the same page with regard
to the expected output. Please have a look at:
https://github.com/s1ck/flink/blob/FLINK-2905/flink-libraries/flink-gelly/src/test/java/org/apache/flink/graph/test/operations/GraphOperationsITCase.java#L360-L703
Of course I will reduce the number of tests in the final version. I just wanted
you to show my expectation of the result.
> Add intersect method to Graph class
> -----------------------------------
>
> Key: FLINK-2905
> URL: https://issues.apache.org/jira/browse/FLINK-2905
> Project: Flink
> Issue Type: New Feature
> Components: Gelly
> Affects Versions: 0.10
> Reporter: Martin Junghanns
> Assignee: Martin Junghanns
> Priority: Minor
>
> Currently, the Gelly Graph supports the set operations
> {{Graph.union(otherGraph)}} and {{Graph.difference(otherGraph)}}. It would be
> nice to have a {{Graph.intersect(otherGraph)}} method, where the resulting
> graph contains all vertices and edges contained in both input graphs.
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