Github user fhueske commented on a diff in the pull request:
https://github.com/apache/flink/pull/1211#discussion_r41389493
--- Diff:
flink-staging/flink-gelly-scala/src/main/scala/org/apache/flink/graph/scala/example/ConnectedComponents.scala
---
@@ -0,0 +1,121 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.graph.scala.example;
+
+import org.apache.flink.api.scala._
+import org.apache.flink.graph.scala._
+import org.apache.flink.graph.Edge
+import org.apache.flink.types.NullValue
+import org.apache.flink.graph.example.utils.ConnectedComponentsDefaultData
+import org.apache.flink.api.common.functions.MapFunction
+import org.apache.flink.graph.library.GSAConnectedComponents
+import java.lang.Long
+
+/**
+ * This example shows how to use Gelly's library methods.
+ * You can find all available library methods in
[[org.apache.flink.graph.library]].
+ *
+ * In particular, this example uses the
+ *
[[org.apache.flink.graph.library.ConnectedComponentsAlgorithm.GSAConnectedComponents]]
+ * library method to compute the connected components of the input graph.
+ *
+ * The input file is a plain text file and must be formatted as follows:
+ * Edges are represented by tuples of srcVertexId, trgVertexId which are
+ * separated by tabs. Edges themselves are separated by newlines.
+ * For example: <code>1\t2\n1\t3\n</code> defines two edges,
+ * 1-2 with and 1-3.
+ *
+ * Usage {{
+ * ConnectedComponents <edge path> <result path> <number of iterations>
+ * }}
+ * If no parameters are provided, the program is run with default data from
+ * [[org.apache.flink.graph.example.utils.ConnectedComponentsDefaultData]]
+ */
+object ConnectedComponents {
+ def main(args: Array[String]) {
+ if (!parseParameters(args)) {
+ return
+ }
+
+ val env = ExecutionEnvironment.getExecutionEnvironment
+ val edges: DataSet[Edge[Long, NullValue]] = getEdgesDataSet(env)
+ val graph = Graph.fromDataSet[Long, Long, NullValue](edges, new
InitVertices, env)
+
+ val components = graph.run(new GSAConnectedComponents[Long,
NullValue](maxIterations))
+
+
+ // emit result
+ if (fileOutput) {
+ components.writeAsCsv(outputPath, "\n", ",")
+ env.execute("Connected Components Example")
+ } else {
+ components.print()
+ }
+ }
+
+ private final class InitVertices extends MapFunction[Long, Long] {
+ override def map(id: Long) = {id}
+ }
+
+ //
***********************************************************************
+ // UTIL METHODS
+ //
***********************************************************************
+
+ private var fileOutput = false
+ private var edgesInputPath: String = null
+ private var outputPath: String = null
+ private var maxIterations =
ConnectedComponentsDefaultData.MAX_ITERATIONS
+
+ private def parseParameters(args: Array[String]): Boolean = {
+ if(args.length > 0) {
+ if(args.length != 3) {
+ System.err.println("Usage ConnectedComponents <edge path>
<output path> " +
+ "<num iterations>")
+ false
--- End diff --
`false` should be on the same indention level as `System.err.println(...)`
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