This is an automated email from the ASF dual-hosted git repository.
desruisseaux pushed a commit to branch geoapi-4.0
in repository https://gitbox.apache.org/repos/asf/sis.git
commit 11eaff770e13b1c311fa033062ce3a91a8dd3ccf
Author: Martin Desruisseaux <martin.desruisse...@geomatys.com>
AuthorDate: Tue Aug 23 19:25:06 2022 +0200
Add overflow-safe `GridExtent.getMedian(int)` method.
Leverage existing methods (minor update).
---
.../org/apache/sis/coverage/grid/GridExtent.java | 33 ++++++++++++++++++++++
.../apache/sis/coverage/grid/GridExtentTest.java | 7 +++--
.../org/apache/sis/internal/util/Numerics.java | 2 ++
.../java/org/apache/sis/math/MathFunctions.java | 2 +-
.../main/java/org/apache/sis/math/Statistics.java | 17 +++++------
5 files changed, 50 insertions(+), 11 deletions(-)
diff --git
a/core/sis-feature/src/main/java/org/apache/sis/coverage/grid/GridExtent.java
b/core/sis-feature/src/main/java/org/apache/sis/coverage/grid/GridExtent.java
index af34fe7c5a..1fdc1aed7f 100644
---
a/core/sis-feature/src/main/java/org/apache/sis/coverage/grid/GridExtent.java
+++
b/core/sis-feature/src/main/java/org/apache/sis/coverage/grid/GridExtent.java
@@ -747,6 +747,39 @@ public class GridExtent implements GridEnvelope,
LenientComparable, Serializable
return coordinates[index + dimension];
}
+ /**
+ * Returns the average of low and high coordinates, rounded toward
positive infinity.
+ * This method is equivalent to computing any of the following,
+ * except that this method does not overflow even if the sum would
overflow:
+ *
+ * <ul>
+ * <li>(<var>low</var> + <var>high</var>) / 2 rounded toward positive
infinity, or</li>
+ * <li>(<var>low</var> + <var>high</var> + 1) / 2 rounded toward
negative infinity.</li>
+ * </ul>
+ *
+ * The two above formulas are equivalent, so the result does not depend
+ * on whether the high coordinate should be inclusive or exclusive.
+ *
+ * @param index the dimension for which to obtain the coordinate value.
+ * @return the median coordinate value at the given dimension.
+ * @throws IndexOutOfBoundsException if the given index is negative or is
equal or greater
+ * than the {@linkplain #getDimension() grid dimension}.
+ *
+ * @since 1.3
+ */
+ public long getMedian(final int index) {
+ final int dimension = getDimension();
+ ArgumentChecks.ensureValidIndex(dimension, index);
+ final long low = coordinates[index];
+ final long high = coordinates[index + dimension];
+ /*
+ * Use `>> 1` instead of `/2` because the two operations differ in
their rounding mode for negative values.
+ * The former rounds toward negative infinity (which is intended here)
while the latter rounds toward zero.
+ * If at least one value is odd, add +1 to the result.
+ */
+ return (low >> 1) + (high >> 1) + ((low | high) & 1);
+ }
+
/**
* Returns the number of integer grid coordinates along the specified
dimension.
* This is equal to {@code getHigh(dimension) - getLow(dimension) + 1}.
diff --git
a/core/sis-feature/src/test/java/org/apache/sis/coverage/grid/GridExtentTest.java
b/core/sis-feature/src/test/java/org/apache/sis/coverage/grid/GridExtentTest.java
index 843d330b46..65cec4bcf4 100644
---
a/core/sis-feature/src/test/java/org/apache/sis/coverage/grid/GridExtentTest.java
+++
b/core/sis-feature/src/test/java/org/apache/sis/coverage/grid/GridExtentTest.java
@@ -34,6 +34,7 @@ import org.apache.sis.referencing.operation.matrix.Matrices;
import org.apache.sis.referencing.operation.matrix.Matrix3;
import org.apache.sis.referencing.crs.HardCodedCRS;
import org.apache.sis.util.resources.Vocabulary;
+import org.apache.sis.internal.util.Numerics;
import org.apache.sis.internal.jdk9.JDK9;
import org.apache.sis.test.TestCase;
import org.junit.Test;
@@ -64,8 +65,10 @@ public final strictfp class GridExtentTest extends TestCase {
* Verifies the low and high values in the specified dimension of the
given extent
*/
static void assertExtentEquals(final GridExtent extent, final int
dimension, final int low, final int high) {
- assertEquals("low", low, extent.getLow (dimension));
- assertEquals("high", high, extent.getHigh(dimension));
+ assertEquals("low", low, extent.getLow (dimension));
+ assertEquals("high", high, extent.getHigh(dimension));
+ assertEquals("size", high - low + 1, extent.getSize(dimension));
+ assertEquals("median", Numerics.ceilDiv(high + low, 2),
extent.getMedian(dimension));
}
/**
diff --git
a/core/sis-utility/src/main/java/org/apache/sis/internal/util/Numerics.java
b/core/sis-utility/src/main/java/org/apache/sis/internal/util/Numerics.java
index 47be423a21..fce0e2b2fc 100644
--- a/core/sis-utility/src/main/java/org/apache/sis/internal/util/Numerics.java
+++ b/core/sis-utility/src/main/java/org/apache/sis/internal/util/Numerics.java
@@ -215,6 +215,8 @@ public final class Numerics extends Static {
* @return x/y rounded toward positive infinity.
*
* @see Math#floorDiv(int, int)
+ *
+ * @todo Replace by {@link Math#ceilDiv(int, int)} in JDK18.
*/
public static int ceilDiv(final int x, final int y) {
int r = x / y;
diff --git
a/core/sis-utility/src/main/java/org/apache/sis/math/MathFunctions.java
b/core/sis-utility/src/main/java/org/apache/sis/math/MathFunctions.java
index 0cdee86f93..ac0b663322 100644
--- a/core/sis-utility/src/main/java/org/apache/sis/math/MathFunctions.java
+++ b/core/sis-utility/src/main/java/org/apache/sis/math/MathFunctions.java
@@ -775,7 +775,7 @@ public final class MathFunctions extends Static {
*/
return Double.NaN;
}
- exp -= (16383 - 1023); // Change from 15 bias to 11 bias.
+ exp -= (16383 - Double.MAX_EXPONENT); // Change from 15 bias to
11 bias.
// Check cases where mantissa excess what double can support.
if (exp < 0) return Double.NEGATIVE_INFINITY;
if (exp > 2046) return Double.POSITIVE_INFINITY;
diff --git a/core/sis-utility/src/main/java/org/apache/sis/math/Statistics.java
b/core/sis-utility/src/main/java/org/apache/sis/math/Statistics.java
index b89e6b50b1..0b1efbbc7a 100644
--- a/core/sis-utility/src/main/java/org/apache/sis/math/Statistics.java
+++ b/core/sis-utility/src/main/java/org/apache/sis/math/Statistics.java
@@ -24,6 +24,7 @@ import org.opengis.util.InternationalString;
import org.apache.sis.util.SimpleInternationalString;
import org.apache.sis.util.ArgumentChecks;
import org.apache.sis.util.resources.Errors;
+import org.apache.sis.internal.util.Numerics;
import org.apache.sis.internal.util.DoubleDouble;
import static java.lang.Math.*;
@@ -612,7 +613,7 @@ public class Statistics implements DoubleConsumer,
LongConsumer, Cloneable, Seri
31 * (doubleToLongBits(maximum) +
31 * (doubleToLongBits(sum) +
31 * (doubleToLongBits(squareSum)))));
- return (int) code ^ (int) (code >>> 32) ^ count;
+ return Long.hashCode(code) ^ count;
}
/**
@@ -624,13 +625,13 @@ public class Statistics implements DoubleConsumer,
LongConsumer, Cloneable, Seri
@Override
public boolean equals(final Object object) {
if (object != null && getClass() == object.getClass()) {
- final Statistics cast = (Statistics) object;
- return count == cast.count && countNaN == cast.countNaN
- && doubleToLongBits(minimum) ==
doubleToLongBits(cast.minimum)
- && doubleToLongBits(maximum) ==
doubleToLongBits(cast.maximum)
- && doubleToLongBits(sum) ==
doubleToLongBits(cast.sum)
- && doubleToLongBits(squareSum) ==
doubleToLongBits(cast.squareSum)
- && Objects.equals(name, cast.name);
+ final Statistics other = (Statistics) object;
+ return count == other.count && countNaN == other.countNaN
+ && Numerics.equals(minimum, other.minimum)
+ && Numerics.equals(maximum, other.maximum)
+ && Numerics.equals(sum, other.sum)
+ && Numerics.equals(squareSum, other.squareSum)
+ && Objects .equals(name, other.name);
}
return false;
}
