Pi estimation example job in Scala

flink-examples/flink-scala-examples/src/main/scala/org/apache/flink/examples/scala/misc/PiEstimation.scala

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+/**
+ * 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.examples.scala.misc
+
+import org.apache.flink.api.scala._
+
+object PiEstimation {
+
+  def main(args: Array[String]) {
+
+    val numSamples: Long = if (args.length > 0) args(0).toLong else 1000000
+
+    val env: ExecutionEnvironment = ExecutionEnvironment.getExecutionEnvironment
+
+    // count how many of the samples would randomly fall into
+    // the unit circle
+    val count =
+      env.generateSequence(1, numSamples)
+      .map (sample => {
+        val x = Math.random()
+        val y = Math.random()
+        if (x * x + y * y < 1) 1L else 0L
+      })
+      .reduce(_+_)
+
+    // the ratio of the unit circle surface to 4 times the unit square is pi
+    val pi = count
+      .map (_ * 4.0 / numSamples)
+
+    println("We estimate Pi to be:")
+
+    pi.print()
+
+    env.execute("PiEstimation example")
+  }
+
+}