diff options
Diffstat (limited to 'docs')
-rw-r--r-- | docs/graphx-programming-guide.md | 33 |
1 files changed, 27 insertions, 6 deletions
diff --git a/docs/graphx-programming-guide.md b/docs/graphx-programming-guide.md index 7f1559d1e2..002ba0cf73 100644 --- a/docs/graphx-programming-guide.md +++ b/docs/graphx-programming-guide.md @@ -84,7 +84,8 @@ import org.apache.spark.graphx._ import org.apache.spark.rdd.RDD {% endhighlight %} -If you are not using the Spark shell you will also need a Spark context. +If you are not using the Spark shell you will also need a `SparkContext`. To learn more about +getting started with Spark refer to the [Spark Quick Start Guide](quick-start.html). # The Property Graph <a name="property_graph"></a> @@ -190,7 +191,7 @@ and `graph.edges` members respectively. {% highlight scala %} val graph: Graph[(String, String), String] // Constructed from above // Count all users which are postdocs -graph.vertices.filter { case (id, (name, pos)) => pos == "postdoc"}.count +graph.vertices.filter { case (id, (name, pos)) => pos == "postdoc" }.count // Count all the edges where src > dst graph.edges.filter(e => e.srcId > e.dstId).count {% endhighlight %} @@ -258,8 +259,10 @@ val graph: Graph[(String, String), String] val indDegrees: VertexRDD[Int] = graph.inDegrees {% endhighlight %} -The reason for differentiating between core graph operations and GraphOps is to be able to support -various graph representations in the future. +The reason for differentiating between core graph operations and [`GraphOps`][GraphOps] is to be +able to support different graph representations in the future. Each graph representation must +provide implementations of the core operations and reuse many of the useful operations defined in +[`GraphOps`][GraphOps]. ## Property Operators @@ -334,14 +337,32 @@ interest or eliminate broken links. For example in the following code we remove [Graph.subgraph]: api/graphx/index.html#org.apache.spark.graphx.Graph@subgraph((EdgeTriplet[VD,ED])⇒Boolean,(VertexID,VD)⇒Boolean):Graph[VD,ED] {% highlight scala %} -val users: RDD[(VertexId, (String, String))] -val edges: RDD[Edge[String]] +// Create an RDD for the vertices +val users: RDD[(VertexID, (String, String))] = + sc.parallelize(Array((3L, ("rxin", "student")), (7L, ("jgonzal", "postdoc")), + (5L, ("franklin", "prof")), (2L, ("istoica", "prof")), + (4L, ("peter", "student")))) +// Create an RDD for edges +val relationships: RDD[Edge[String]] = + sc.parallelize(Array(Edge(3L, 7L, "collab"), Edge(5L, 3L, "advisor"), + Edge(2L, 5L, "colleague"), Edge(5L, 7L, "pi"), + Edge(4L, 0L, "student"), Edge(5L, 0L, "colleague"))) // Define a default user in case there are relationship with missing user val defaultUser = ("John Doe", "Missing") // Build the initial Graph val graph = Graph(users, relationships, defaultUser) +// Notice that there is a user 0 (for which we have no information) connecting users +// 4 (peter) and 5 (franklin). +graph.triplets.map( + triplet => triplet.srcAttr._1 + " is the " + triplet.attr + " of " + triplet.dstAttr._1 + ).collect.foreach(println(_)) // Remove missing vertices as well as the edges to connected to them val validGraph = graph.subgraph(vpred = (id, attr) => attr._2 != "Missing") +// The valid subgraph will disconnect users 4 and 5 by removing user 0 +validGraph.vertices.collect.foreach(println(_)) +validGraph.triplets.map( + triplet => triplet.srcAttr._1 + " is the " + triplet.attr + " of " + triplet.dstAttr._1 + ).collect.foreach(println(_)) {% endhighlight %} > Note in the above example only the vertex predicate is provided. The `subgraph` operator defaults |