TEXT-126: Adding Sorensen-Dice similarity algoritham

src/main/java/org/apache/commons/text/similarity/SorensenDicesSimilarity.java

@@ -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.text.similarity;
+
+import java.util.HashSet;
+import java.util.Set;
+
+/**
+ *
+ * @since 1.7
+ */
+public class SorensenDicesSimilarity implements SimilarityScore<Double> {
+
+    /**
+     * @param left  the first CharSequence, must not be null
+     * @param right the second CharSequence, must not be null
+     * @return result similarity
+     * @throws IllegalArgumentException if either CharSequence input is {@code null}
+     */
+
+    @Override
+    public Double apply(final CharSequence left, final CharSequence right) {
+
+        if (left == null || right == null) {
+            throw new IllegalArgumentException("CharSequences must not be null");
+        }
+
+        if (left.equals(right)) {
+            return 1d;
+        }
+
+        if ("".equals(left) || "".equals(right)) {
+            return 0d;
+        }
+
+        Set<String> nLeft = new HashSet<String>();
+        Set<String> nRight = new HashSet<String>();
+
+        for (int i = 0; i < left.length() - 1; i++) {
+            char chr = left.charAt(i);
+            char nextChr = left.charAt(i + 1);
+            String bi = "" + chr + nextChr;
+            nLeft.add(bi);
+        }
+        for (int j = 0; j < right.length() - 1; j++) {
+            char chr = right.charAt(j);
+            char nextChr = right.charAt(j + 1);
+            String bi = "" + chr + nextChr;
+            nRight.add(bi);
+        }
+
+        final int total = nLeft.size() + nRight.size();
+        final Set<String> union = new HashSet<String>(total);
+        union.addAll(nLeft);
+        union.addAll(nRight);
+
+        final int intersection = total - union.size();
+        return (2.0d * intersection) / total;
+    }
+}

src/test/java/org/apache/commons/text/similarity/SorensenDicesSimilarityTest.java

@@ -0,0 +1,80 @@
+/*
+ * 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.text.similarity;
+
+import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+
+/**
+ * Unit tests for {@link SorensenDicesSimilarity}.
+ */
+public class SorensenDicesSimilarityTest {
+
+    private static SorensenDicesSimilarity similarity;
+
+    @BeforeAll
+    public static void setUp() {
+        similarity = new SorensenDicesSimilarity();
+    }
+
+    @Test
+    public void testGetJaroWinklerSimilarity_StringString() {
+
+        assertEquals(1d, similarity.apply("", ""));
+        assertEquals(1.0d, similarity.apply("foo", "foo"));
+        assertEquals(0.8d, similarity.apply("foo", "foo "));
+        assertEquals(0.4d, similarity.apply("frog", "fog"));
+        assertEquals(0.0d, similarity.apply("fly", "ant"));
+        assertEquals(0.0d, similarity.apply("elephant", "hippo"));
+        assertEquals(0.0d, similarity.apply("hippo", "elephant"));
+        assertEquals(0.0d, similarity.apply("hippo", "zzzzzzzz"));
+        assertEquals(0.5d, similarity.apply("hello", "hallo"));
+        assertEquals(0.7d, similarity.apply("ABC Corporation", "ABC Corp"));
+        assertEquals(0.7391304347826086d, similarity.apply("D N H Enterprises Inc", "D & H Enterprises, Inc."));
+        assertEquals(0.8076923076923077d,
+                similarity.apply("My Gym Children's Fitness Center", "My Gym. Childrens Fitness"));
+        assertEquals(0.6956521739130435, similarity.apply("PENNSYLVANIA", "PENNCISYLVNIA"));
+        assertEquals(0.9230769230769231, similarity.apply("/opt/software1", "/opt/software2"));
+        assertEquals(0.5d, similarity.apply("aaabcd", "aaacdb"));
+        assertEquals(0.631578947368421, similarity.apply("John Horn", "John Hopkins"));
+
+    }
+
+    @Test
+    public void testGetDicesCoefficientSimilarity_NullNull() {
+        assertThatIllegalArgumentException().isThrownBy(() -> {
+            similarity.apply(null, null);
+        });
+    }
+
+    @Test
+    public void testGetDicesCoefficientSimilarity_StringNull() {
+        assertThatIllegalArgumentException().isThrownBy(() -> {
+            similarity.apply(" ", null);
+        });
+    }
+
+    @Test
+    public void testGetDicesCoefficientSimilarity_NullString() {
+        assertThatIllegalArgumentException().isThrownBy(() -> {
+            similarity.apply(null, "clear");
+        });
+    }
+}