[#944] Change to originality score and new threshold value

src/main/java/reposense/authorship/analyzer/AuthorshipAnalyzer.java

@@ -23,7 +23,7 @@
 public class AuthorshipAnalyzer {
  private static final Logger logger = LogsManager.getLogger(AuthorshipAnalyzer.class);
 
- private static final double SIMILARITY_THRESHOLD = 0.8;
+ private static final double ORIGINALITY_THRESHOLD = 0.51;
 
  private static final String DIFF_FILE_CHUNK_SEPARATOR = "\ndiff --git a/.*\n";
  private static final Pattern FILE_CHANGED_PATTERN =
@@ -55,10 +55,10 @@ public static boolean analyzeAuthorship(RepoConfiguration config, String filePat
  return true;
  }
 
- CandidateLine deletedLine = getDeletedLineWithHighestSimilarity(config, filePath, lineContent, commitHash);
+ CandidateLine deletedLine = getDeletedLineWithLowestOriginality(config, filePath, lineContent, commitHash);
 
- // Give full credit if there are no deleted lines found or deleted line is less than similarity threshold
- if (deletedLine == null || deletedLine.getSimilarityScore() < SIMILARITY_THRESHOLD) {
+ // Give full credit if there are no deleted lines found or deleted line is more than originality threshold
+ if (deletedLine == null || deletedLine.getOriginalityScore() > ORIGINALITY_THRESHOLD) {
  return true;
  }
 
@@ -84,14 +84,14 @@ public static boolean analyzeAuthorship(RepoConfiguration config, String filePat
  }
 
  /**
- * Returns the deleted line in {@code commitHash} that has the highest similarity with {@code lineContent}.
+ * Returns the deleted line in {@code commitHash} that has the lowest originality with {@code lineContent}.
  */
- private static CandidateLine getDeletedLineWithHighestSimilarity(RepoConfiguration config, String filePath,
+ private static CandidateLine getDeletedLineWithLowestOriginality(RepoConfiguration config, String filePath,
  String lineContent, String commitHash) {
  String gitLogResults = GitLog.getParentCommits(config.getRepoRoot(), commitHash);
  String[] parentCommits = gitLogResults.split(" ");
 
- CandidateLine highestSimilarityLine = null;
+ CandidateLine lowestOriginalityLine = null;
 
  for (String parentCommit : parentCommits) {
  // Generate diff between commit and parent commit
@@ -112,28 +112,28 @@ private static CandidateLine getDeletedLineWithHighestSimilarity(RepoConfigurati
  continue;
  }
 
- CandidateLine candidateLine = getDeletedLineWithHighestSimilarityInDiff(
+ CandidateLine candidateLine = getDeletedLineWithLowestOriginalityInDiff(
  fileDiffResult, lineContent, parentCommit, preImageFilePath);
  if (candidateLine == null) {
  continue;
  }
 
- if (highestSimilarityLine == null
- || candidateLine.getSimilarityScore() > highestSimilarityLine.getSimilarityScore()) {
- highestSimilarityLine = candidateLine;
+ if (lowestOriginalityLine == null
+ || candidateLine.getOriginalityScore() < lowestOriginalityLine.getOriginalityScore()) {
+ lowestOriginalityLine = candidateLine;
  }
  }
  }
 
- return highestSimilarityLine;
+ return lowestOriginalityLine;
  }
 
  /**
- * Returns the deleted line in {@code fileDiffResult} that has the highest similarity with {@code lineContent}.
+ * Returns the deleted line in {@code fileDiffResult} that has the lowest originality with {@code lineContent}.
  */
- private static CandidateLine getDeletedLineWithHighestSimilarityInDiff(String fileDiffResult, String lineContent,
+ private static CandidateLine getDeletedLineWithLowestOriginalityInDiff(String fileDiffResult, String lineContent,
  String commitHash, String filePath) {
- CandidateLine highestSimilarityLine = null;
+ CandidateLine lowestOriginalityLine = null;
 
  String[] hunks = fileDiffResult.split(HUNK_SEPARATOR);
 
@@ -155,11 +155,13 @@ private static CandidateLine getDeletedLineWithHighestSimilarityInDiff(String fi
 
  if (lineChanged.startsWith(DELETED_LINE_SYMBOL)) {
  String deletedLineContent = lineChanged.substring(DELETED_LINE_SYMBOL.length());
- double similarityScore = similarityScore(lineContent, deletedLineContent);
+ double originalityScore = computeOriginalityScore(lineContent, deletedLineContent);
 
- if (highestSimilarityLine == null || similarityScore > highestSimilarityLine.getSimilarityScore()) {
- highestSimilarityLine = new CandidateLine(
- currentPreImageLineNumber, deletedLineContent, filePath, commitHash, similarityScore);
+ if (lowestOriginalityLine == null
+ || originalityScore < lowestOriginalityLine.getOriginalityScore()) {
+ lowestOriginalityLine = new CandidateLine(
+ currentPreImageLineNumber, deletedLineContent, filePath, commitHash,
+ originalityScore);
  }
  }
 
@@ -169,7 +171,7 @@ private static CandidateLine getDeletedLineWithHighestSimilarityInDiff(String fi
  }
  }
 
- return highestSimilarityLine;
+ return lowestOriginalityLine;
  }
 
  /**
@@ -191,11 +193,11 @@ private static int getPreImageStartingLineNumber(String linesChangedHeader) {
  }
 
  /**
- * Calculates the similarity score of {@code s} with {@code baseString}.
+ * Calculates the originality score of {@code s} with {@code baseString}.
  */
- private static double similarityScore(String s, String baseString) {
+ private static double computeOriginalityScore(String s, String baseString) {
  double levenshteinDistance = StringsUtil.getLevenshteinDistance(s, baseString);
- return 1 - (levenshteinDistance / baseString.length());
+ return levenshteinDistance / baseString.length();
  }
 
  /**

src/main/java/reposense/authorship/model/CandidateLine.java

@@ -8,15 +8,15 @@ public class CandidateLine {
  private final String lineContent;
  private final String filePath;
  private final String gitBlameCommitHash;
- private final double similarityScore;
+ private final double originalityScore;
 
  public CandidateLine(int lineNumber, String lineContent, String filePath, String gitBlameCommitHash,
- double similarityScore) {
+ double originalityScore) {
  this.lineNumber = lineNumber;
  this.lineContent = lineContent;
  this.filePath = filePath;
  this.gitBlameCommitHash = gitBlameCommitHash;
- this.similarityScore = similarityScore;
+ this.originalityScore = originalityScore;
  }
 
  public int getLineNumber() {
@@ -35,7 +35,7 @@ public String getGitBlameCommitHash() {
  return gitBlameCommitHash;
  }
 
- public double getSimilarityScore() {
- return similarityScore;
+ public double getOriginalityScore() {
+ return originalityScore;
  }
 }