Author: erans
Date: Fri Aug 17 15:09:59 2012
New Revision: 1374308
URL: http://svn.apache.org/viewvc?rev=1374308&view=rev
Log:
Code cleanup: moved all computations to the constructor, allowing to make
the class immutable.
Modified:
commons/proper/math/trunk/src/main/java/org/apache/commons/math3/optimization/fitting/HarmonicFitter.java
commons/proper/math/trunk/src/test/java/org/apache/commons/math3/optimization/fitting/HarmonicFitterTest.java
Modified:
commons/proper/math/trunk/src/main/java/org/apache/commons/math3/optimization/fitting/HarmonicFitter.java
URL:
http://svn.apache.org/viewvc/commons/proper/math/trunk/src/main/java/org/apache/commons/math3/optimization/fitting/HarmonicFitter.java?rev=1374308&r1=1374307&r2=1374308&view=diff
==============================================================================
---
commons/proper/math/trunk/src/main/java/org/apache/commons/math3/optimization/fitting/HarmonicFitter.java
(original)
+++
commons/proper/math/trunk/src/main/java/org/apache/commons/math3/optimization/fitting/HarmonicFitter.java
Fri Aug 17 15:09:59 2012
@@ -177,20 +177,21 @@ public class HarmonicFitter extends Curv
* number of measurements.</p>
*/
public static class ParameterGuesser {
- /** Sampled observations. */
- private final WeightedObservedPoint[] observations;
/** Amplitude. */
- private double a;
+ private final double a;
/** Angular frequency. */
- private double omega;
+ private final double omega;
/** Phase. */
- private double phi;
+ private final double phi;
/**
* Simple constructor.
- * @param observations sampled observations
- * @throws NumberIsTooSmallException if the sample is too short or if
- * the first guess cannot be computed.
+ *
+ * @param observations Sampled observations.
+ * @throws NumberIsTooSmallException if the sample is too short.
+ * @throws ZeroException if the abscissa range is zero.
+ * @throws MathIllegalStateException when the guessing procedure cannot
+ * produce sensible results.
*/
public ParameterGuesser(WeightedObservedPoint[] observations) {
if (observations.length < 4) {
@@ -198,7 +199,13 @@ public class HarmonicFitter extends Curv
observations.length, 4,
true);
}
- this.observations = observations.clone();
+ final WeightedObservedPoint[] sorted =
sortObservations(observations);
+
+ final double aOmega[] = guessAOmega(sorted);
+ a = aOmega[0];
+ omega = aOmega[1];
+
+ phi = guessPhi(sorted);
}
/**
@@ -212,16 +219,18 @@ public class HarmonicFitter extends Curv
* </ul>
*/
public double[] guess() {
- sortObservations();
- guessAOmega();
- guessPhi();
return new double[] { a, omega, phi };
}
/**
* Sort the observations with respect to the abscissa.
+ *
+ * @param unsorted Input observations.
+ * @return the input observations, sorted.
*/
- private void sortObservations() {
+ private WeightedObservedPoint[]
sortObservations(WeightedObservedPoint[] unsorted) {
+ final WeightedObservedPoint[] observations = unsorted.clone();
+
// Since the samples are almost always already sorted, this
// method is implemented as an insertion sort that reorders the
// elements in place. Insertion sort is very efficient in this
case.
@@ -243,6 +252,8 @@ public class HarmonicFitter extends Curv
curr = observations[j];
}
}
+
+ return observations;
}
/**
@@ -250,11 +261,16 @@ public class HarmonicFitter extends Curv
* This method assumes that the {@link #sortObservations()} method
* has been called previously.
*
+ * @param observations Observations, sorted w.r.t. abscissa.
* @throws ZeroException if the abscissa range is zero.
* @throws MathIllegalStateException when the guessing procedure cannot
* produce sensible results.
+ * @return the guessed amplitude (at index 0) and circular frequency
+ * (at index 1).
*/
- private void guessAOmega() {
+ private double[] guessAOmega(WeightedObservedPoint[] observations) {
+ final double[] aOmega = new double[2];
+
// initialize the sums for the linear model between the two
integrals
double sx2 = 0;
double sy2 = 0;
@@ -305,7 +321,7 @@ public class HarmonicFitter extends Curv
if (xRange == 0) {
throw new ZeroException();
}
- omega = 2 * Math.PI / xRange;
+ aOmega[1] = 2 * Math.PI / xRange;
double yMin = Double.POSITIVE_INFINITY;
double yMax = Double.NEGATIVE_INFINITY;
@@ -318,7 +334,7 @@ public class HarmonicFitter extends Curv
yMax = y;
}
}
- a = 0.5 * (yMax - yMin);
+ aOmega[0] = 0.5 * (yMax - yMin);
} else {
if (c2 == 0) {
// In some ill-conditioned cases (cf. MATH-844), the
guesser
@@ -326,15 +342,20 @@ public class HarmonicFitter extends Curv
throw new
MathIllegalStateException(LocalizedFormats.ZERO_DENOMINATOR);
}
- a = FastMath.sqrt(c1 / c2);
- omega = FastMath.sqrt(c2 / c3);
+ aOmega[0] = FastMath.sqrt(c1 / c2);
+ aOmega[1] = FastMath.sqrt(c2 / c3);
}
+
+ return aOmega;
}
/**
* Estimate a first guess of the phase.
+ *
+ * @param observations Observations, sorted w.r.t. abscissa.
+ * @return the guessed phase.
*/
- private void guessPhi() {
+ private double guessPhi(WeightedObservedPoint[] observations) {
// initialize the means
double fcMean = 0;
double fsMean = 0;
@@ -356,7 +377,7 @@ public class HarmonicFitter extends Curv
fsMean += omega * currentY * sine + currentYPrime * cosine;
}
- phi = FastMath.atan2(-fsMean, fcMean);
+ return FastMath.atan2(-fsMean, fcMean);
}
}
}
Modified:
commons/proper/math/trunk/src/test/java/org/apache/commons/math3/optimization/fitting/HarmonicFitterTest.java
URL:
http://svn.apache.org/viewvc/commons/proper/math/trunk/src/test/java/org/apache/commons/math3/optimization/fitting/HarmonicFitterTest.java?rev=1374308&r1=1374307&r2=1374308&view=diff
==============================================================================
---
commons/proper/math/trunk/src/test/java/org/apache/commons/math3/optimization/fitting/HarmonicFitterTest.java
(original)
+++
commons/proper/math/trunk/src/test/java/org/apache/commons/math3/optimization/fitting/HarmonicFitterTest.java
Fri Aug 17 15:09:59 2012
@@ -191,14 +191,12 @@ public class HarmonicFitterTest {
points[i] = new WeightedObservedPoint(1, i, y[i]);
}
- final HarmonicFitter.ParameterGuesser guesser
- = new HarmonicFitter.ParameterGuesser(points);
-
// The guesser fails because the function is far from an harmonic
// function: It is a triangular periodic function with amplitude 3
// and period 12, and all sample points are taken at integer abscissae
// so function values all belong to the integer subset {-3, -2, -1, 0,
// 1, 2, 3}.
- guesser.guess();
+ final HarmonicFitter.ParameterGuesser guesser
+ = new HarmonicFitter.ParameterGuesser(points);
}
}
