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Posted to issues@spark.apache.org by "Glenn Strycker (JIRA)" <ji...@apache.org> on 2014/05/20 00:25:38 UTC

[jira] [Created] (SPARK-1885) GraphX reduce function not working properly -- returns only 1 element

Glenn Strycker created SPARK-1885:
-------------------------------------

             Summary: GraphX reduce function not working properly -- returns only 1 element
                 Key: SPARK-1885
                 URL: https://issues.apache.org/jira/browse/SPARK-1885
             Project: Spark
          Issue Type: Bug
            Reporter: Glenn Strycker


When .reduce() is performed on an EdgeRDD of length n, the result is only 1 element value instead of n.

Given a graph object "orig_graph", I have the following output for the edge list:

scala> orig_graph.edges.collect
= Array(Edge(1,4,1), Edge(1,5,1), Edge(1,7,1), Edge(2,5,1), Edge(2,6,1), Edge(3,5,1), Edge(3,6,1), Edge(3,7,1), Edge(4,1,1), Edge(5,1,1), Edge(5,2,1), Edge(5,3,1), Edge(6,2,1), Edge(6,3,1), Edge(7,1,1), Edge(7,3,1))

When I apply a map function (with _.copy() commands added, as per https://issues.apache.org/jira/browse/SPARK-1188), it looks ok:

scala> orig_graph.edges.map(_.copy()).flatMap(edge => Seq(edge) ).map(edge => (Edge(edge.copy().srcId, edge.copy().dstId, edge.copy().attr), 1)).collect

= Array((Edge(1,4,1),1), (Edge(1,5,1),1), (Edge(1,7,1),1), (Edge(2,5,1),1), (Edge(2,6,1),1), (Edge(3,5,1),1), (Edge(3,6,1),1), (Edge(3,7,1),1), (Edge(4,1,1),1), (Edge(5,1,1),1), (Edge(5,2,1),1), (Edge(5,3,1),1), (Edge(6,2,1),1), (Edge(6,3,1),1), (Edge(7,1,1),1), (Edge(7,3,1),1))

BUT NOW, when I run the following, I only get 1 element returned:

scala> orig_graph.edges.map(_.copy()).flatMap(edge => Seq(edge) ).map(edge => (Edge(edge.copy().srcId, edge.copy().dstId, edge.copy().attr), 1)).reduce( (A,B) => { if (A._1.dstId == B._1.srcId) (Edge(A._1.srcId, B._1.dstId, 2), 1) else if (A._1.srcId == B._1.dstId) (Edge(B._1.srcId, A._1.dstId, 2), 1) else (Edge(0, 0, A._1.srcId.toInt*A._1.dstId.toInt*B._1.srcId.toInt*B._1.dstId.toInt), A._1.srcId.toInt*A._1.dstId.toInt*B._1.srcId.toInt*B._1.dstId.toInt) } )

= (Edge(0,0,0),0)



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