More similarity metrics

core/src/main/java/de/jplag/JPlagResult.java

@@ -1,5 +1,6 @@
 package de.jplag;
 
+import java.util.Arrays;
 import java.util.List;
 import java.util.function.ToDoubleFunction;
 
@@ -11,6 +12,7 @@
  * Encapsulates the results of a comparison of a set of source code submissions.
  */
 public class JPlagResult {
+    private final static int SIMILARITY_DISTRIBUTION_SIZE = 100;
 
     private List<JPlagComparison> comparisons; // comparisons whose similarity was about the specified threshold
 
@@ -23,7 +25,6 @@ public class JPlagResult {
     private final int[] similarityDistribution; // 10-element array representing the similarity distribution of the detected matches.
 
     private List<ClusteringResult<Submission>> clusteringResult;
-    private final int SIMILARITY_DISTRIBUTION_SIZE = 100;
 
     public JPlagResult(List<JPlagComparison> comparisons, SubmissionSet submissions, long durationInMillis, JPlagOptions options) {
         // sort by similarity (descending)
@@ -34,15 +35,6 @@ public JPlagResult(List<JPlagComparison> comparisons, SubmissionSet submissions,
         similarityDistribution = calculateSimilarityDistribution(comparisons);
     }
 
-    /**
-     * Drops elements from the comparison list to free memory. Note, that this affects the similarity distribution and is
-     * only meant to be used if you don't need the information about comparisons with lower match similarity anymore.
-     * @param limit the number of comparisons to keep in the list
-     */
-    public void dropComparisons(int limit) {
-        this.comparisons = this.getComparisons(limit);
-    }
-
     public void setClusteringResult(List<ClusteringResult<Submission>> clustering) {
         this.clusteringResult = clustering;
     }
@@ -127,6 +119,10 @@ public String toString() {
                 getDuration(), getOptions().language().getName(), submissions.numberOfSubmissions());
     }
 
+    public List<Integer> calculateDistributionFor(ToDoubleFunction<JPlagComparison> similarityMetric) {
+        return Arrays.stream(calculateDistributionFor(this.comparisons, similarityMetric)).boxed().toList();
+    }
+
     /**
      * Note: Before, comparisons with a similarity below the given threshold were also included in the similarity matrix.
      */

core/src/main/java/de/jplag/options/SimilarityMetric.java

@@ -1,14 +1,27 @@
 package de.jplag.options;
 
+import java.util.HashMap;
+import java.util.Map;
 import java.util.function.ToDoubleFunction;
 
 import de.jplag.JPlagComparison;
+import de.jplag.Match;
 
 public enum SimilarityMetric implements ToDoubleFunction<JPlagComparison> {
     AVG("average similarity", JPlagComparison::similarity),
     MIN("minimum similarity", JPlagComparison::minimalSimilarity),
     MAX("maximal similarity", JPlagComparison::maximalSimilarity),
-    INTERSECTION("matched tokens", it -> (double) it.getNumberOfMatchedTokens());
+    INTERSECTION("matched tokens", it -> (double) it.getNumberOfMatchedTokens()),
+    SYMMETRIC("symmetric similarity", it -> {
+        int divisor = it.firstSubmission().getNumberOfTokens() + it.secondSubmission().getNumberOfTokens();
+        if (divisor != 0) {
+            return 2.0 * it.getNumberOfMatchedTokens() / divisor;
+        } else {
+            return .0;
+        }
+    }),
+    LONGEST_MATCH("number of tokens in the longest match", it -> it.matches().stream().mapToInt(Match::length).max().orElse(0)),
+    OVERALL("Sum of both submission lengths", it -> it.firstSubmission().getNumberOfTokens() + it.secondSubmission().getNumberOfTokens());
 
     private final ToDoubleFunction<JPlagComparison> similarityFunction;
     private final String description;
@@ -31,4 +44,12 @@ public double applyAsDouble(JPlagComparison comparison) {
     public String toString() {
         return description;
     }
+
+    public static Map<String, Double> createSimilarityMap(JPlagComparison comparison) {
+        Map<String, Double> result = new HashMap<>();
+        for (SimilarityMetric metric : SimilarityMetric.values()) {
+            result.put(metric.name(), metric.applyAsDouble(comparison));
+        }
+        return result;
+    }
 }

core/src/main/java/de/jplag/reporting/jsonfactory/ComparisonReportWriter.java

@@ -1,9 +1,6 @@
 package de.jplag.reporting.jsonfactory;
 
-import java.util.Comparator;
-import java.util.List;
-import java.util.Map;
-import java.util.Objects;
+import java.util.*;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.function.Function;
@@ -56,8 +53,7 @@ private void writeComparisons(String path, List<JPlagComparison> comparisons) {
             String secondSubmissionId = submissionToIdFunction.apply(comparison.secondSubmission());
             String fileName = generateComparisonName(firstSubmissionId, secondSubmissionId);
             addToLookUp(firstSubmissionId, secondSubmissionId, fileName);
-            var comparisonReport = new ComparisonReport(firstSubmissionId, secondSubmissionId,
-                    Map.of(SimilarityMetric.AVG.name(), comparison.similarity(), SimilarityMetric.MAX.name(), comparison.maximalSimilarity()),
+            var comparisonReport = new ComparisonReport(firstSubmissionId, secondSubmissionId, SimilarityMetric.createSimilarityMap(comparison),
                     convertMatchesToReportMatches(comparison));
             fileWriter.saveAsJSON(comparisonReport, path, fileName);
         });
@@ -98,7 +94,7 @@ private Match convertMatchToReportMatch(JPlagComparison comparison, de.jplag.Mat
         List<Token> tokensFirst = comparison.firstSubmission().getTokenList().subList(match.startOfFirst(), match.endOfFirst() + 1);
         List<Token> tokensSecond = comparison.secondSubmission().getTokenList().subList(match.startOfSecond(), match.endOfSecond() + 1);
 
-        Comparator<? super Token> lineComparator = (first, second) -> first.getLine() - second.getLine();
+        Comparator<? super Token> lineComparator = Comparator.comparingInt(Token::getLine);
 
         Token startOfFirst = tokensFirst.stream().min(lineComparator).orElseThrow();
         Token endOfFirst = tokensFirst.stream().max(lineComparator).orElseThrow();

core/src/main/java/de/jplag/reporting/reportobject/mapper/MetricMapper.java

@@ -1,13 +1,10 @@
 package de.jplag.reporting.reportobject.mapper;
 
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.Collections;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.function.Function;
 
-import de.jplag.JPlagComparison;
 import de.jplag.JPlagResult;
 import de.jplag.Submission;
 import de.jplag.options.SimilarityMetric;
@@ -29,8 +26,11 @@ public MetricMapper(Function<Submission, String> submissionToIdFunction) {
      * @return Map with key as name of metric and value as distribution
      */
     public static Map<String, List<Integer>> getDistributions(JPlagResult result) {
-        return Map.of(SimilarityMetric.AVG.name(), convertDistribution(result.getSimilarityDistribution()), SimilarityMetric.MAX.name(),
-                convertDistribution(result.getMaxSimilarityDistribution()));
+        Map<String, List<Integer>> distributions = new HashMap<>();
+        for (SimilarityMetric metric : SimilarityMetric.values()) {
+            distributions.put(metric.name(), result.calculateDistributionFor(metric));
+        }
+        return distributions;
     }
 
     /**
@@ -41,17 +41,7 @@ public static Map<String, List<Integer>> getDistributions(JPlagResult result) {
     public List<TopComparison> getTopComparisons(JPlagResult result) {
         return result.getComparisons(result.getOptions().maximumNumberOfComparisons()).stream()
                 .map(comparison -> new TopComparison(submissionToIdFunction.apply(comparison.firstSubmission()),
-                        submissionToIdFunction.apply(comparison.secondSubmission()), getComparisonMetricMap(comparison)))
+                        submissionToIdFunction.apply(comparison.secondSubmission()), SimilarityMetric.createSimilarityMap(comparison)))
                 .toList();
     }
-
-    private Map<String, Double> getComparisonMetricMap(JPlagComparison comparison) {
-        return Map.of(SimilarityMetric.AVG.name(), comparison.similarity(), SimilarityMetric.MAX.name(), comparison.maximalSimilarity());
-    }
-
-    private static List<Integer> convertDistribution(int[] array) {
-        List<Integer> list = new ArrayList<>(Arrays.stream(array).boxed().toList());
-        Collections.reverse(list);
-        return list;
-    }
 }

core/src/test/java/de/jplag/reporting/reportobject/mapper/MetricMapperTest.java

@@ -5,7 +5,8 @@
 import static org.mockito.Mockito.mock;
 
 import java.util.ArrayList;
-import java.util.Collections;
+import java.util.Arrays;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 
@@ -16,6 +17,7 @@
 import de.jplag.JPlagResult;
 import de.jplag.Submission;
 import de.jplag.options.JPlagOptions;
+import de.jplag.options.SimilarityMetric;
 import de.jplag.reporting.reportobject.model.TopComparison;
 
 public class MetricMapperTest {
@@ -39,7 +41,8 @@ public void test_getDistributions() {
         Map<String, List<Integer>> result = MetricMapper.getDistributions(jPlagResult);
 
         // then
-        Assertions.assertEquals(Map.of("AVG", EXPECTED_AVG_DISTRIBUTION, "MAX", EXPECTED_MAX_DISTRIBUTION), result);
+        Assertions.assertEquals(EXPECTED_AVG_DISTRIBUTION, result.get("AVG"));
+        Assertions.assertEquals(EXPECTED_MAX_DISTRIBUTION, result.get("MAX"));
     }
 
     @Test
@@ -53,13 +56,11 @@ public void test_getTopComparisons() {
 
         // then
         Assertions.assertEquals(
-                List.of(new TopComparison("1", "2", Map.of("AVG", .7, "MAX", .8)), new TopComparison("3", "4", Map.of("AVG", .3, "MAX", .9))),
-                result);
+                List.of(new TopComparison("1", "2", buildSimilarityMap(.7, .8)), new TopComparison("3", "4", buildSimilarityMap(.3, .9))), result);
     }
 
     private int[] distribution(List<Integer> expectedDistribution) {
         var reversedDistribution = new ArrayList<>(expectedDistribution);
-        Collections.reverse(reversedDistribution);
         return reversedDistribution.stream().mapToInt(Integer::intValue).toArray();
     }
 
@@ -76,6 +77,9 @@ private JPlagResult createJPlagResult(int[] avgDistribution, int[] maxDistributi
         doReturn(avgDistribution).when(jPlagResult).getSimilarityDistribution();
         doReturn(maxDistribution).when(jPlagResult).getMaxSimilarityDistribution();
 
+        doReturn(Arrays.stream(avgDistribution).boxed().toList()).when(jPlagResult).calculateDistributionFor(SimilarityMetric.AVG);
+        doReturn(Arrays.stream(maxDistribution).boxed().toList()).when(jPlagResult).calculateDistributionFor(SimilarityMetric.MAX);
+
         JPlagOptions options = mock(JPlagOptions.class);
         doReturn(createComparisonsDto.length).when(options).maximumNumberOfComparisons();
         doReturn(options).when(jPlagResult).getOptions();
@@ -105,4 +109,14 @@ private record Comparison(CreateSubmission submission1, CreateSubmission submiss
     private record CreateSubmission(String name) {
     }
 
+    private Map<String, Double> buildSimilarityMap(double avg, double max) {
+        Map<String, Double> map = new HashMap<>();
+        for (SimilarityMetric value : SimilarityMetric.values()) {
+            map.put(value.name(), 0d);
+        }
+        map.put(SimilarityMetric.AVG.name(), avg);
+        map.put(SimilarityMetric.MAX.name(), max);
+        return map;
+    }
+
 }

endtoend-testing/src/main/java/de/jplag/endtoend/model/ExpectedResult.java

@@ -24,6 +24,7 @@ public double getSimilarityForMetric(SimilarityMetric metric) {
             case MIN -> resultSimilarityMinimum();
             case MAX -> resultSimilarityMaximum();
             case INTERSECTION -> resultMatchedTokenNumber();
+            default -> throw new IllegalArgumentException(String.format("Similarity metric %s not supported for end to end tests", metric.name()));
         };
     }