Check-in commons-math 3.6.1 am: 1354beaf45 am: 0018f64b87 am: b3715644fb am: 5484895ffd am: 029d049e49HEADandroid-14.0.0_r37android-14.0.0_r36android-14.0.0_r35android-14.0.0_r34android-14.0.0_r33android-14.0.0_r32android-14.0.0_r31android-14.0.0_r30android-14.0.0_r29mastermainandroid14-qpr2-s5-releaseandroid14-qpr2-s4-releaseandroid14-qpr2-s3-releaseandroid14-qpr2-s2-releaseandroid14-qpr2-s1-releaseandroid14-qpr2-release

Original change: https://android-review.googlesource.com/c/platform/external/apache-commons-math/+/2702413

Change-Id: I6451550459c6d42417e3214f1db820289d799bc7
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>

1 files changed, 46 insertions, 0 deletions

diff --git a/src/main/java/org/apache/commons/math3/ml/distance/CanberraDistance.java b/src/main/java/org/apache/commons/math3/ml/distance/CanberraDistance.java
new file mode 100644
index 0000000..d467c3b
--- /dev/null
+++ b/src/main/java/org/apache/commons/math3/ml/distance/CanberraDistance.java
@@ -0,0 +1,46 @@
+/*
+ * 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.ml.distance;
+
+import org.apache.commons.math3.exception.DimensionMismatchException;
+import org.apache.commons.math3.util.FastMath;
+import org.apache.commons.math3.util.MathArrays;
+
+/**
+ * Calculates the Canberra distance between two points.
+ *
+ * @since 3.2
+ */
+public class CanberraDistance implements DistanceMeasure {
+
+    /** Serializable version identifier. */
+    private static final long serialVersionUID = -6972277381587032228L;
+
+    /** {@inheritDoc} */
+    public double compute(double[] a, double[] b)
+    throws DimensionMismatchException {
+        MathArrays.checkEqualLength(a, b);
+        double sum = 0;
+        for (int i = 0; i < a.length; i++) {
+            final double num = FastMath.abs(a[i] - b[i]);
+            final double denom = FastMath.abs(a[i]) + FastMath.abs(b[i]);
+            sum += num == 0.0 && denom == 0.0 ? 0.0 : num / denom;
+        }
+        return sum;
+    }
+
+}