Github user greghogan commented on a diff in the pull request:
https://github.com/apache/flink/pull/3802#discussion_r114085668
--- Diff:
flink-libraries/flink-gelly/src/main/java/org/apache/flink/graph/generator/CirculantGraph.java
---
@@ -0,0 +1,141 @@
+/*
+ * 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.generator;
+
+import org.apache.flink.api.common.functions.FlatMapFunction;
+import org.apache.flink.api.java.DataSet;
+import org.apache.flink.api.java.ExecutionEnvironment;
+import org.apache.flink.api.java.functions.FunctionAnnotation;
+import org.apache.flink.graph.Edge;
+import org.apache.flink.graph.Graph;
+import org.apache.flink.graph.Vertex;
+import org.apache.flink.types.LongValue;
+import org.apache.flink.types.NullValue;
+import org.apache.flink.util.Collector;
+import org.apache.flink.util.LongValueSequenceIterator;
+import org.apache.flink.util.Preconditions;
+
+import java.util.HashSet;
+import java.util.Set;
+
+/*
+ * @see <a
href="http://mathworld.wolfram.com/CirculantGraph.html";>Circulant Graph at
Wolfram MathWorld</a>
+ */
+public class CirculantGraph
+extends AbstractGraphGenerator<LongValue, NullValue, NullValue> {
+
+ public static final int MINIMUM_VERTEX_COUNT = 1;
+
+ public static final int MINIMUM_OFFSET = 1;
+
+ // Required to create the DataSource
+ private final ExecutionEnvironment env;
+
+ // Required configuration
+ private long vertexCount;
+
+ private Set<Long> signedOffsets = new HashSet<>();
+
+ /**
+ * An undirected {@link Graph} whose {@link Vertex} connects to targets
appointed by an offset list.
+ *
+ * @param env the Flink execution environment
+ * @param vertexCount number of vertices
+ */
+ public CirculantGraph(ExecutionEnvironment env, long vertexCount) {
+ Preconditions.checkArgument(vertexCount >= MINIMUM_VERTEX_COUNT,
+ "Vertex count must be at least " +
MINIMUM_VERTEX_COUNT);
+
+ this.env = env;
+ this.vertexCount = vertexCount;
+ }
+
+ /**
+ * Required configuration for each offset of the graph.
+ *
+ * @param offset appoint the vertices' position should be linked by any
vertex
+ * @return this
+ */
+ public CirculantGraph addOffset(long offset) {
--- End diff --
By making this a `range` with both `offset` and `length` then users need
not specifying hundreds or thousands of consecutive offsets. Will make use on
the command line much simpler, and there is also less data for Flink to
broadcast.
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