Glenn Strycker created SPARK-1885:
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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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