[GitHub] [commons-text] kinow commented on a change in pull request #103: TEXT-126: Adding Sorensen-Dice similarity algoritham

[GitBox <gi...@apache.org>]

kinow commented on a change in pull request #103: TEXT-126: Adding Sorensen-Dice similarity algoritham
URL: https://github.com/apache/commons-text/pull/103#discussion_r263986006
 
 

 ##########
 File path: src/main/java/org/apache/commons/text/similarity/SorensenDiceSimilarity.java
 ##########
 @@ -0,0 +1,127 @@
+/*
+ * 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;
+import java.util.stream.Collectors;
+
+import org.apache.commons.lang3.StringUtils;
+
+/**
+ * A similarity algorithm indicating the percentage of matched characters
+ * between two character sequences.
+ *
+ * <p>
+ * The S&#248;rensen–Dice coefficient is a statistic used for comparing the
+ * similarity of two samples. It was independently developed by the botanists
+ * Thorvald S&#248;rensen and Lee Raymond Dice, who published in 1948 and 1945
+ * respectively. The index is known by several other names, especially
+ * S&#248;rensen–Dice index, S&#248;rensen index and Dice's coefficient. Other
+ * variations include the "similarity coefficient" or "index", such as Dice
+ * similarity coefficient (DSC).
+ * </p>
+ *
+ * <p>
+ * This implementation is based on the S&#248;rensen–Dice similarity algorithm
+ * from <a href=
+ * "http://en.wikipedia.org/wiki/S%C3%B8rensen%E2%80%93Dice_coefficient">
+ * http://en.wikipedia.org/wiki/S%C3%B8rensen%E2%80%93Dice_coefficient</a>.
+ *
+ *
+ * </p>
+ *
+ * @since 1.7
+ */
+public class SorensenDiceSimilarity implements SimilarityScore<Double> {
+
+    /**
+     * Calculates Sorensen-Dice Similarity of two character sequences passed as
+     * input.
+     *
+     * <pre>
+     * similarity.apply(null, null)                 = IllegalArgumentException
+     * similarity.apply("foo", null)                = IllegalArgumentException
+     * similarity.apply(null, "foo")                = IllegalArgumentException
+     * similarity.apply("night", "nacht")           = 0.25
+     * similarity.apply("", "")                     = 1.0
+     * similarity.apply("foo", "foo")               = 1.0
+     * similarity.apply("foo", "foo ")              = 0.8
+     * similarity.apply("foo", "foo ")              = 0.66
+     * similarity.apply("foo", " foo ")             = 0.66
+     * similarity.apply("foo", " foo")              = 0.66
+     * similarity.apply("", "a")                    = 0.0
+     * similarity.apply("aaapppp", "")              = 0.0
+     * similarity.apply("frog", "fog")              = 0.4
+     * similarity.apply("fly", "ant")               = 0.0
+     * similarity.apply("elephant", "hippo")        = 0.0
+     * similarity.apply("hippo", "elephant")        = 0.0
+     * similarity.apply("hippo", "zzzzzzzz")        = 0.0
+     * similarity.apply("hello", "hallo")           = 0.5
+     * similarity.apply("ABC Corporation", "ABC Corp") = 0.7
+     * similarity.apply("D N H Enterprises Inc", "D &amp; H Enterprises, Inc.") = 0.74
+     * similarity.apply("My Gym Children's Fitness Center", "My Gym. Childrens Fitness") = 0.81
+     * similarity.apply("PENNSYLVANIA", "PENNCISYLVNIA") = 0.69
+     * </pre>
+     *
+     * @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 (StringUtils.equals(left, right)) {
 
 Review comment:
   +1, this would be a more homogeneous approach for the library. We can review this later for 2.0 if necessary.

----------------------------------------------------------------
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
 
For queries about this service, please contact Infrastructure at:
users@infra.apache.org


With regards,
Apache Git Services