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25 changes: 23 additions & 2 deletions core/src/main/scala/org/graphframes/GraphFrame.scala
Original file line number Diff line number Diff line change
Expand Up @@ -1081,10 +1081,31 @@ object GraphFrame extends Serializable with Logging {
* @group conversions
*/
def fromEdges(e: DataFrame): GraphFrame = {
fromEdges(e, StorageLevel.MEMORY_AND_DISK)
}

/**
* Create a new [[GraphFrame]] from an edge `DataFrame`. The resulting [[GraphFrame]] will have
* [[GraphFrame.vertices]] with a single "id" column.
*
* Note: The [[GraphFrame.vertices]] DataFrame will be persisted at level
* `StorageLevel.MEMORY_AND_DISK`.
* @param e
* Edge DataFrame. This must include columns "src" and "dst" containing source and destination
* vertex IDs. All other columns are treated as edge attributes.
* @param storageLevel
* StorageLevel to persist the graph vertices
* @return
* New [[GraphFrame]] instance
*
* @group conversions
*/
def fromEdges(e: DataFrame, storageLevel: StorageLevel): GraphFrame = {
logWarn(
s"this method persists graph vertices with storage level ${storageLevel.toString()}, users should manually unpersist it when the graph is not needed!")
val srcs = e.select(e("src").as("id"))
val dsts = e.select(e("dst").as("id"))
val v = srcs.unionAll(dsts).distinct()
v.persist(StorageLevel.MEMORY_AND_DISK)
val v = srcs.unionAll(dsts).distinct().persist(storageLevel)
apply(v, e)
}

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39 changes: 39 additions & 0 deletions core/src/test/scala/org/graphframes/GraphFrameSuite.scala
Original file line number Diff line number Diff line change
Expand Up @@ -157,6 +157,45 @@ class GraphFrameSuite extends SparkFunSuite with GraphFrameTestSparkContext {
.collect()
.toSet
assert(idsFromVerticesSet === idsFromEdgesSet)
g.vertices.unpersist()
}

test("construction from edges DataFrame, string IDs") {
val edges = spark
.createDataFrame(Seq(("a", "b", "love"), ("b", "a", "hate"), ("b", "c", "follow")))
.toDF("src", "dst", "action")

val g = GraphFrame.fromEdges(edges)
assert(g.vertices.columns === Array("id"))
val idsFromVertices = g.vertices.select("id").rdd.map(_.getString(0)).collect()
val idsFromVerticesSet = idsFromVertices.toSet
assert(idsFromVertices.length === idsFromVerticesSet.size)
val idsFromEdgesSet = g.edges
.select("src", "dst")
.rdd
.flatMap {
case Row(src: String, dst: String) =>
Seq(src, dst)
case _: Row => throw new GraphFramesUnreachableException()
}
.collect()
.toSet
assert(idsFromVerticesSet === idsFromEdgesSet)
g.vertices.unpersist()
}

test("construction from edges DataFrame, different storage level") {
val edges = spark
.createDataFrame(Seq((1L, 2L, "love"), (2L, 1L, "hate"), (2L, 3L, "follow")))
.toDF("src", "dst", "action")

var g = GraphFrame.fromEdges(edges)
assert(g.vertices.storageLevel === StorageLevel.MEMORY_AND_DISK)
g.vertices.unpersist()

g = GraphFrame.fromEdges(edges, StorageLevel.MEMORY_AND_DISK_SER)
assert(g.vertices.storageLevel === StorageLevel.MEMORY_AND_DISK_SER)
g.vertices.unpersist()
}

test("construction from GraphX") {
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