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From t.@apache.org
Subject svn commit: r1308151 - in /commons/proper/math/trunk/src: changes/changes.xml main/java/org/apache/commons/math3/genetics/FixedElapsedTime.java test/java/org/apache/commons/math3/genetics/FixedElapsedTimeTest.java
Date Sun, 01 Apr 2012 16:46:01 GMT
Author: tn
Date: Sun Apr  1 16:46:01 2012
New Revision: 1308151

URL: http://svn.apache.org/viewvc?rev=1308151&view=rev
Log:
Added FixedElapsedTime stopping condition.
JIRA: MATH-773 contributed by Reid Hochstedler

Added:
    commons/proper/math/trunk/src/main/java/org/apache/commons/math3/genetics/FixedElapsedTime.java
  (with props)
    commons/proper/math/trunk/src/test/java/org/apache/commons/math3/genetics/FixedElapsedTimeTest.java
  (with props)
Modified:
    commons/proper/math/trunk/src/changes/changes.xml

Modified: commons/proper/math/trunk/src/changes/changes.xml
URL: http://svn.apache.org/viewvc/commons/proper/math/trunk/src/changes/changes.xml?rev=1308151&r1=1308150&r2=1308151&view=diff
==============================================================================
--- commons/proper/math/trunk/src/changes/changes.xml (original)
+++ commons/proper/math/trunk/src/changes/changes.xml Sun Apr  1 16:46:01 2012
@@ -52,6 +52,9 @@ If the output is not quite correct, chec
   <body>
     <release version="3.1" date="TBD" description="
 ">
+      <action dev="tn" type="add" issue="MATH-773" due-to="Reid Hochstedler">
+        Added class FixedElapsedTime (new StoppingCondition for evolution of generations)
to genetics package.
+      </action>
       <action dev="celestin" type="add" issue="MATH-756">
         Added classes Decimal64 and Decimal64Field, which are wrapper classes around primitive
doubles. These classes implement FieldElement and Field, respectively.
       </action>

Added: commons/proper/math/trunk/src/main/java/org/apache/commons/math3/genetics/FixedElapsedTime.java
URL: http://svn.apache.org/viewvc/commons/proper/math/trunk/src/main/java/org/apache/commons/math3/genetics/FixedElapsedTime.java?rev=1308151&view=auto
==============================================================================
--- commons/proper/math/trunk/src/main/java/org/apache/commons/math3/genetics/FixedElapsedTime.java
(added)
+++ commons/proper/math/trunk/src/main/java/org/apache/commons/math3/genetics/FixedElapsedTime.java
Sun Apr  1 16:46:01 2012
@@ -0,0 +1,81 @@
+/*
+ * 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.commons.math3.genetics;
+
+import java.util.concurrent.TimeUnit;
+
+import org.apache.commons.math3.exception.NumberIsTooSmallException;
+
+/**
+ * Stops after a fixed amount of time has elapsed.
+ *
+ * <p>
+ * The first time {@link #isSatisfied(Population)} is invoked, the end time of
+ * the evolution is determined based on the provided <code>maxTime</code> value.
+ * Once the elapsed time reaches the configured <code>maxTime</code> value,
+ * {@link #isSatisfied(Population)} returns true.
+ * </p>
+ *
+ * @version $Id$
+ * @since 3.1
+ */
+public class FixedElapsedTime implements StoppingCondition {
+    /** Maximum allowed time period (in nanoseconds). */
+    private final long maxTimePeriod;
+
+    /** The predetermined termination time (stopping condition). */
+    private long endTime = -1;
+
+    /**
+     * Create a new {@link FixedElapsedTime} instance.
+     *
+     * @param maxTime maximum number of seconds generations are allowed to evolve
+     * @throws NumberIsTooSmallException if the provided time is &lt; 0
+     */
+    public FixedElapsedTime(final long maxTime) {
+        this(maxTime, TimeUnit.SECONDS);
+    }
+
+    /**
+     * Create a new {@link FixedElapsedTime} instance.
+     *
+     * @param maxTime maximum time generations are allowed to evolve
+     * @param unit {@link TimeUnit} of the maxTime argument
+     * @throws NumberIsTooSmallException if the provided time is &lt; 0
+     */
+    public FixedElapsedTime(final long maxTime, final TimeUnit unit) {
+        if (maxTime < 0) {
+            throw new NumberIsTooSmallException(maxTime, 0, true);
+        }
+        maxTimePeriod = unit.toNanos(maxTime);
+    }
+
+    /**
+     * Determine whether or not the maximum allowed time has passed.
+     * The termination time is determined after the first generation.
+     *
+     * @param population ignored (no impact on result)
+     * @return <code>true</code> IFF the maximum allowed time period has elapsed
+     */
+    public boolean isSatisfied(final Population population) {
+        if (endTime < 0) {
+            endTime = System.nanoTime() + maxTimePeriod;
+        }
+
+        return System.nanoTime() >= endTime;
+    }
+}

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Added: commons/proper/math/trunk/src/test/java/org/apache/commons/math3/genetics/FixedElapsedTimeTest.java
URL: http://svn.apache.org/viewvc/commons/proper/math/trunk/src/test/java/org/apache/commons/math3/genetics/FixedElapsedTimeTest.java?rev=1308151&view=auto
==============================================================================
--- commons/proper/math/trunk/src/test/java/org/apache/commons/math3/genetics/FixedElapsedTimeTest.java
(added)
+++ commons/proper/math/trunk/src/test/java/org/apache/commons/math3/genetics/FixedElapsedTimeTest.java
Sun Apr  1 16:46:01 2012
@@ -0,0 +1,74 @@
+/*
+ * 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.commons.math3.genetics;
+
+import java.util.Iterator;
+import java.util.concurrent.TimeUnit;
+
+import org.apache.commons.math3.util.FastMath;
+import org.junit.Assert;
+import org.junit.Test;
+
+public class FixedElapsedTimeTest {
+
+    @Test
+    public void testIsSatisfied() {
+        final Population pop = new Population() {
+            public void addChromosome(final Chromosome chromosome) {
+                // unimportant
+            }
+            public Chromosome getFittestChromosome() {
+                // unimportant
+                return null;
+            }
+            public int getPopulationLimit() {
+                // unimportant
+                return 0;
+            }
+            public int getPopulationSize() {
+                // unimportant
+                return 0;
+            }
+            public Population nextGeneration() {
+                // unimportant
+                return null;
+            }
+            public Iterator<Chromosome> iterator() {
+                // unimportant
+                return null;
+            }
+        };
+
+        final long start = System.nanoTime();
+        final long duration = 3;
+        final FixedElapsedTime tec = new FixedElapsedTime(duration, TimeUnit.SECONDS);
+
+        while (!tec.isSatisfied(pop)) {
+            try {
+                Thread.sleep(500);
+            } catch (InterruptedException e) {
+                // ignore
+            }
+        }
+
+        final long end = System.nanoTime();
+        final long elapsedTime = end - start;
+        final long diff = FastMath.abs(elapsedTime - TimeUnit.SECONDS.toNanos(duration));
+
+        Assert.assertTrue(diff < TimeUnit.MILLISECONDS.toNanos(100));
+    }
+}

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