aherbert 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_r260927842
########## File path: 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)) { Review comment: Also note that you are calling `String.equals(Object)` which only compares to another `String`. In this case if the argument **is** a `String` then `String.length()` will be faster logic. For any other `CharSequence` this logic will fail as it will be ignored by `String.equals(Object)`. You should look at the JDK 1.8 source code for `String.contentEquals(CharSequence)`. Then decide how fast that will be compared to known implementations of `length()` in JDK 1.8 [CharSequence](https://docs.oracle.com/javase/8/docs/api/java/lang/CharSequence.html) or the commons-text `TextStringBuilder.length()`. Most implementations I found just return an `int`. `CharBuffer` returns the computation of one `int` minus another `int`. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org With regards, Apache Git Services --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org For additional commands, e-mail: dev-h...@commons.apache.org
