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* Add forward and backward difference. * PartialDerivative: add tests * POM: bump parent to pom-imglib2 10.0.2 This makes the class LoopBuilder available. * PartialDerivative: use LoopBuilder to get clean code * Add formulae for finite diffierence methods Addresses comments in #44 Also adds formulae for central difference * Update author list of PartialDerivative.java Added: - @tibuch - @maarzt
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src/test/java/net/imglib2/algorithm/gradient/PartialDerivativeTest.java
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,100 @@ | ||
| package net.imglib2.algorithm.gradient; | ||
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| import net.imglib2.Interval; | ||
| import net.imglib2.RandomAccessibleInterval; | ||
| import net.imglib2.img.array.ArrayImgs; | ||
| import net.imglib2.type.numeric.real.DoubleType; | ||
| import net.imglib2.util.Intervals; | ||
| import net.imglib2.view.Views; | ||
| import org.junit.Test; | ||
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| import java.util.ArrayList; | ||
| import java.util.List; | ||
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| import static junit.framework.TestCase.assertTrue; | ||
| import static org.junit.Assert.assertArrayEquals; | ||
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| /** | ||
| * Tests {@link PartialDerivative}. | ||
| * | ||
| * @author Matthias Arzt | ||
| */ | ||
| public class PartialDerivativeTest | ||
| { | ||
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| private final double DELTA = 0.0001; | ||
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| private final RandomAccessibleInterval< DoubleType > testImage = | ||
| createImage2dMinSizeValues( /* min: */ 0, 0, /* size: */ 5, 3, /* values: */ | ||
| 0.0, 0.0, 0.0, 0.0, 0.0, | ||
| 0.0, 2.0, 0.0, -1.0, 0.0, | ||
| 0.0, 0.0, 5.0, 0.0, 0.0 | ||
| ); | ||
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| private final RandomAccessibleInterval< DoubleType > centralDifferenceExpected = | ||
| createImage2dMinSizeValues( /* min: */ 1, 0, /* size: */ 3, 3, /* values: */ | ||
| 0.0, 0.0, 0.0, | ||
| 0.0, -1.5, 0.0, | ||
| 2.5, 0.0, -2.5 | ||
| ); | ||
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| private final RandomAccessibleInterval< DoubleType > backwardDifferenceExpected = | ||
| createImage2dMinSizeValues( /* min: */ 1, 0, /* size: */ 4, 3, /* values: */ | ||
| 0.0, 0.0, 0.0, 0.0, | ||
| 2.0, -2.0, -1.0, 1.0, | ||
| 0.0, 5.0, -5.0, 0.0 | ||
| ); | ||
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| public static RandomAccessibleInterval< DoubleType > createImage2dMinSizeValues( long minX, long minY, long sizeX, long sizeY, double... values ) | ||
| { | ||
| Interval interval = Intervals.createMinSize( minX, minY, sizeX, sizeY ); | ||
| return Views.translate( ArrayImgs.doubles( values, Intervals.dimensionsAsLongArray( interval ) ), | ||
| Intervals.minAsLongArray( interval ) ); | ||
| } | ||
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| @Test | ||
| public void testGradientCentralDifferenceX() | ||
| { | ||
| RandomAccessibleInterval< DoubleType > data = testImage; | ||
| RandomAccessibleInterval< DoubleType > result = emptyArrayImg( centralDifferenceExpected ); | ||
| PartialDerivative.gradientCentralDifference( data, result, 0 ); | ||
| assertImagesEqual( centralDifferenceExpected, result ); | ||
| } | ||
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| @Test | ||
| public void testGradientBackwardDifferenceX() | ||
| { | ||
| RandomAccessibleInterval< DoubleType > data = testImage; | ||
| RandomAccessibleInterval< DoubleType > result = emptyArrayImg( backwardDifferenceExpected ); | ||
| PartialDerivative.gradientBackwardDifference( data, result, 0 ); | ||
| assertImagesEqual( backwardDifferenceExpected, result ); | ||
| } | ||
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| @Test | ||
| public void testForwardDifferenceX() | ||
| { | ||
| RandomAccessibleInterval< DoubleType > data = testImage; | ||
| RandomAccessibleInterval< DoubleType > expected = Views.translate( backwardDifferenceExpected, -1, 0 ); | ||
| RandomAccessibleInterval< DoubleType > result = emptyArrayImg( expected ); | ||
| PartialDerivative.gradientForwardDifference( data, result, 0 ); | ||
| assertImagesEqual( expected, result ); | ||
| } | ||
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| private void assertImagesEqual( RandomAccessibleInterval< DoubleType > expected, RandomAccessibleInterval< DoubleType > actual ) | ||
| { | ||
| assertTrue( Intervals.equals( expected, actual ) ); | ||
| assertArrayEquals( imageAsArray( expected ), imageAsArray( actual ), DELTA ); | ||
| } | ||
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| private double[] imageAsArray( RandomAccessibleInterval< DoubleType > image ) | ||
| { | ||
| List< Double > values = new ArrayList<>(); | ||
| Views.iterable( image ).forEach( x -> values.add( x.getRealDouble() ) ); | ||
| return values.stream().mapToDouble( x -> x ).toArray(); | ||
| } | ||
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| private RandomAccessibleInterval< DoubleType > emptyArrayImg( Interval interval ) | ||
| { | ||
| return Views.translate( ArrayImgs.doubles( Intervals.dimensionsAsLongArray( interval ) ), Intervals.minAsLongArray( interval ) ); | ||
| } | ||
| } |