Github user shghatge commented on a diff in the pull request:
https://github.com/apache/flink/pull/847#discussion_r33823720
--- Diff:
flink-staging/flink-gelly/src/main/java/org/apache/flink/graph/GraphCsvReader.java
---
@@ -0,0 +1,471 @@
+/*
+ * 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;
+import com.google.common.base.Preconditions;
+import org.apache.flink.api.common.functions.MapFunction;
+import org.apache.flink.api.java.DataSet;
+import org.apache.flink.api.java.io.CsvReader;
+import org.apache.flink.api.java.tuple.Tuple2;
+import org.apache.flink.api.java.tuple.Tuple3;
+import org.apache.flink.core.fs.Path;
+import org.apache.flink.api.java.ExecutionEnvironment;
+import org.apache.flink.types.NullValue;
+/**
+ * A class to build a Graph using path(s) provided to CSV file(s) with
edge (vertices) data
+ * The class also configures the CSV readers used to read edges(vertices)
data such as the field types,
+ * the delimiters (row and field), the fields that should be included or
skipped, and other flags
+ * such as whether to skip the initial line as the header.
+ * The configuration is done using the functions provided in The {@link
org.apache.flink.api.java.io.CsvReader} class.
+ */
+public class GraphCsvReader<K,VV,EV> {
+
+ private final Path vertexPath,edgePath;
+ private final ExecutionEnvironment executionContext;
+ protected CsvReader EdgeReader;
+ protected CsvReader VertexReader;
+ protected MapFunction<K, VV> mapper;
+
+//--------------------------------------------------------------------------------------------------------------------
+
+ public GraphCsvReader(Path vertexPath,Path edgePath,
ExecutionEnvironment context) {
+ this.vertexPath = vertexPath;
+ this.edgePath = edgePath;
+ this.VertexReader = new CsvReader(vertexPath,context);
+ this.EdgeReader = new CsvReader(edgePath,context);
+ this.mapper=null;
+ this.executionContext=context;
+ }
+
+ public GraphCsvReader(Path edgePath, ExecutionEnvironment context) {
+ this.vertexPath = null;
+ this.edgePath = edgePath;
+ this.EdgeReader = new CsvReader(edgePath,context);
+ this.VertexReader = null;
+ this.mapper = null;
+ this.executionContext=context;
+ }
+
+ public GraphCsvReader(Path edgePath,final MapFunction<K, VV> mapper,
ExecutionEnvironment context) {
+ this.vertexPath = null;
+ this.edgePath = edgePath;
+ this.EdgeReader = new CsvReader(edgePath,context);
+ this.VertexReader = null;
+ this.mapper = mapper;
+ this.executionContext=context;
+ }
+
+ public GraphCsvReader (String edgePath,ExecutionEnvironment context) {
+ this(new Path(Preconditions.checkNotNull(edgePath, "The file
path may not be null.")), context);
+
+ }
+
+ public GraphCsvReader(String vertexPath, String edgePath,
ExecutionEnvironment context) {
+ this(new Path(Preconditions.checkNotNull(vertexPath, "The file
path may not be null.")),new Path(Preconditions.checkNotNull(edgePath, "The
file path may not be null.")), context);
+ }
+
+
+ public GraphCsvReader (String edgePath, final MapFunction<K, VV>
mapper, ExecutionEnvironment context) {
+ this(new Path(Preconditions.checkNotNull(edgePath, "The
file path may not be null.")),mapper, context);
+ }
+
+ public CsvReader getEdgeReader() {
+ return this.EdgeReader;
+ }
+
+ public CsvReader getVertexReader() {
+ return this.VertexReader;
+ }
+
//--------------------------------------------------------------------------------------------------------------------
+
+ /**
+ * Specifies the types for the Graph fields and returns a Graph with
those field types
+ *
+ * This method is overloaded for the case in which Vertices don't have
a value
+ *
+ * @param type0 The type of CSV field 0 and 1 for the CSV reader used
for reading Edge data, the type of CSV field 0 for the CSV reader used for
reading Vertex data and the type of Vetex ID in the returned Graph.
--- End diff --
Yes. I explained how it is passed to the edgeReader and vertexReader and at
the end what it signifies in the graph. i.e. Key type for vertex. Should I only
keep the last part?
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