feat: median default grade tally

README.md

@@ -140,17 +140,17 @@ ResultInterface result = mj.deliberate(tally);
 	- [x] Ranking
 - [x] Release v0.1.0
 - [x] Guess the amount of judges
-- [ ] Allow defining a default grade
+- [x] Allow defining a default grade
 	- [x] Static Grade (configurable)
-	- [x] Normalization (using least common multiple)
-	- [ ] Median Grade
+	- [x] Normalization (using Least Common Multiple)
+	- [x] Median Grade
 - [ ] Release v0.2.0
 - [ ] Publish on package repositories
     - [ ] Gradle
     - [ ] Maven
     - [ ] … ? (please share your knowledge to help us!)
 - [ ] Release v0.3.0
-- [ ] Use it somewhere in another app, adjust API as needed (one last time)
+- [ ] Use it somewhere in an application, adjust API as needed (one last time)
 - [ ] Release v1.0.0
 
 

src/main/java/fr/mieuxvoter/mj/MedianDefaultTally.java

@@ -0,0 +1,43 @@
+package fr.mieuxvoter.mj;
+
+import java.math.BigInteger;
+
+/**
+ * Fill the missing judgments into the median grade.
+ * Useful when the proposals have not received the exact same amount of votes and
+ * the median grade is considered a sane default.
+ */
+public class MedianDefaultTally extends Tally implements TallyInterface {
+
+	public MedianDefaultTally(ProposalTallyInterface[] proposalsTallies, BigInteger amountOfJudges) {
+		super(proposalsTallies, amountOfJudges);
+		fillWithDefaultGrade();
+	}
+
+	public MedianDefaultTally(ProposalTallyInterface[] proposalsTallies, Long amountOfJudges) {
+		super(proposalsTallies, amountOfJudges);
+		fillWithDefaultGrade();
+	}
+
+	public MedianDefaultTally(ProposalTallyInterface[] proposalsTallies, Integer amountOfJudges) {
+		super(proposalsTallies, amountOfJudges);
+		fillWithDefaultGrade();
+	}
+
+	protected void fillWithDefaultGrade() {
+		int amountOfProposals = getAmountOfProposals();
+		for (int i = 0 ; i < amountOfProposals ; i++) {
+			ProposalTallyInterface proposal = getProposalsTallies()[i];
+			ProposalTallyAnalysis analysis = new ProposalTallyAnalysis(proposal);
+			Integer defaultGrade = analysis.getMedianGrade();
+			BigInteger amountOfJudgments = proposal.getAmountOfJudgments();
+			BigInteger missingAmount = this.amountOfJudges.subtract(amountOfJudgments);
+			int missingSign = missingAmount.compareTo(BigInteger.ZERO);
+			assert(0 <= missingSign);  // ERROR: More judgments than judges!
+			if (0 < missingSign) {
+				proposal.getTally()[defaultGrade] = proposal.getTally()[defaultGrade].add(missingAmount); 
+			}
+		}
+	}
+
+}

src/test/java/fr/mieuxvoter/mj/MajorityJudgmentDeliberatorTest.java

@@ -213,7 +213,7 @@ class MajorityJudgmentDeliberatorTest {
 	}
 
 	@Test
-	@DisplayName("Test static default grade with thousands of proposals")
+	@DisplayName("Test static default grade with thousands of proposals and millions of judges")
 	public void testStaticDefaultWithThousandsOfProposals() {
 		int amountOfProposals = 1337;
 		Integer amountOfJudges = 60000000;
@@ -257,6 +257,30 @@ class MajorityJudgmentDeliberatorTest {
 //		}
 //	}
 
+	@Test
+	@DisplayName("Test with a median default grade")
+	public void testMedianDefaultGrade() {
+		Integer amountOfJudges = 42;
+		DeliberatorInterface mj = new MajorityJudgmentDeliberator();
+		TallyInterface tally = new MedianDefaultTally(new ProposalTallyInterface[] {
+				new ProposalTally(new Integer[]{ 0, 0, 1 }),
+				new ProposalTally(new Integer[]{ 0, 1, 0 }),
+				new ProposalTally(new Integer[]{ 1, 1, 1 }),
+				new ProposalTally(new Integer[]{ 1, 0, 1 }),
+				new ProposalTally(new Integer[]{ 1, 0, 0 }),
+		}, amountOfJudges);
+		
+		ResultInterface result = mj.deliberate(tally);
+		
+		assertNotNull(result);
+		assertEquals(5, result.getProposalResults().length);
+		assertEquals(1, result.getProposalResults()[0].getRank());
+		assertEquals(2, result.getProposalResults()[1].getRank());
+		assertEquals(3, result.getProposalResults()[2].getRank());
+		assertEquals(4, result.getProposalResults()[3].getRank());
+		assertEquals(5, result.getProposalResults()[4].getRank());
+	}
+
 	@Test
 	@DisplayName("Test normalized tallies with thousands of (prime) proposals")
 	public void testNormalizedWithThousandsOfPrimeProposals() {