Added calculation of constituency results

2023-07-02 18:04:03 +02:00
parent 681b738919
commit 30d2c39580
11 changed files with 455 additions and 0 deletions
@@ -0,0 +1,16 @@
+package de.twomartens.wahlrecht.model;
+
+import lombok.Getter;
+import lombok.RequiredArgsConstructor;
+import lombok.Setter;
+import lombok.ToString;
+
+@RequiredArgsConstructor
+@Getter
+@Setter
+@ToString
+public class Candidate {
+  private final String name;
+  private final String profession;
+  private Elected elected = Elected.NOT_ELECTED;
+}
@@ -0,0 +1,9 @@
+package de.twomartens.wahlrecht.model;
+
+public record Constituency(String name, int numberOfSeats) {
+
+  @Override
+  public String toString() {
+    return name;
+  }
+}
@@ -0,0 +1,7 @@
+package de.twomartens.wahlrecht.model;
+
+public enum Elected {
+  NOT_ELECTED,
+  CONSTITUENCY,
+  OVERALL
+}
@@ -0,0 +1,12 @@
+package de.twomartens.wahlrecht.model;
+
+import java.util.Collection;
+import java.util.Deque;
+import java.util.Map;
+import lombok.Builder;
+
+@Builder
+public record ElectedResult(Map<Nomination, Collection<Candidate>> electedCandidates,
+                            Deque<Double> usedElectionNumbers) {
+
+}
@@ -0,0 +1,10 @@
+package de.twomartens.wahlrecht.model;
+
+import java.time.LocalDate;
+import java.util.Collection;
+
+public record Election(String name, LocalDate day, VotingThreshold votingThreshold,
+                       int totalNumberOfSeats,
+                       Collection<Constituency> constituencies) {
+
+}
@@ -0,0 +1,45 @@
+package de.twomartens.wahlrecht.model;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import lombok.Getter;
+import lombok.RequiredArgsConstructor;
+import lombok.Setter;
+import lombok.ToString;
+import lombok.ToString.Include;
+
+@RequiredArgsConstructor
+@ToString(onlyExplicitlyIncluded = true)
+public class Nomination {
+  private final List<Candidate> candidates = new ArrayList<>();
+  private final Map<Candidate, Integer> candidateToPosition = new HashMap<>();
+  private final Map<Integer, Candidate> positionToCandidate = new HashMap<>();
+  @Include
+  private final String name;
+  @Getter
+  private final boolean supportVotesOnNomination;
+  @Getter
+  @Setter
+  private VotingResult votingResult;
+
+  private void addCandidate(Candidate candidate) {
+    candidates.add(candidate);
+    candidateToPosition.put(candidate, candidates.size());
+    positionToCandidate.put(candidates.size(), candidate);
+  }
+
+  public void addCandidates(Candidate... candidates) {
+    Arrays.stream(candidates).forEach(this::addCandidate);
+  }
+
+  public Candidate getCandidate(int position) {
+    return positionToCandidate.get(position);
+  }
+
+  public int getPosition(Candidate candidate) {
+    return candidateToPosition.get(candidate);
+  }
+}
@@ -0,0 +1,21 @@
+package de.twomartens.wahlrecht.model;
+
+import java.util.Map;
+import lombok.Getter;
+import lombok.RequiredArgsConstructor;
+import lombok.Setter;
+
+@RequiredArgsConstructor
+@Setter
+@Getter
+public class Party {
+  private final String name;
+  private Nomination overallNomination;
+  private Map<Constituency, Nomination> constituencyNominations;
+  private boolean passesVotingThreshold;
+
+  @Override
+  public String toString() {
+    return name;
+  }
+}
@@ -0,0 +1,27 @@
+package de.twomartens.wahlrecht.model;
+
+import java.util.Map;
+import lombok.Builder;
+import lombok.Getter;
+
+@Getter
+public class VotingResult {
+
+  private final int votesOnNomination;
+  private final Map<Integer, Integer> votesPerPosition;
+  private Integer totalVotes = null;
+
+  @Builder
+  public VotingResult(int votesOnNomination, Map<Integer, Integer> votesPerPosition) {
+    this.votesOnNomination = votesOnNomination;
+    this.votesPerPosition = votesPerPosition;
+  }
+
+  public int getTotalVotes() {
+    if (totalVotes == null) {
+      totalVotes = votesOnNomination + votesPerPosition.values().stream()
+          .reduce(0, Integer::sum);
+    }
+    return totalVotes;
+  }
+}
@@ -0,0 +1,15 @@
+package de.twomartens.wahlrecht.model;
+
+import lombok.AccessLevel;
+import lombok.Getter;
+import lombok.RequiredArgsConstructor;
+
+@Getter
+@RequiredArgsConstructor(access = AccessLevel.PRIVATE)
+public enum VotingThreshold {
+  NONE(0.00),
+  THREE(0.03),
+  FIVE(0.05);
+
+  private final double multiplier;
+}
@@ -0,0 +1,141 @@
+package de.twomartens.wahlrecht.service;
+
+import de.twomartens.wahlrecht.model.Candidate;
+import de.twomartens.wahlrecht.model.Constituency;
+import de.twomartens.wahlrecht.model.ElectedResult;
+import de.twomartens.wahlrecht.model.Nomination;
+import de.twomartens.wahlrecht.model.VotingResult;
+import java.util.ArrayDeque;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Comparator;
+import java.util.Deque;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.stream.Collectors;
+import org.springframework.lang.NonNull;
+import org.springframework.stereotype.Service;
+
+@Service
+public class ConstituencyCalculationService {
+  private final Deque<Double> electionNumberHistory = new ArrayDeque<>();
+
+  public ElectedResult calculateConstituency(@NonNull Constituency constituency,
+      @NonNull Collection<Nomination> nominations) {
+    electionNumberHistory.clear();
+    int totalVotes = nominations.stream()
+        .map(Nomination::getVotingResult)
+        .map(VotingResult::getTotalVotes)
+        .reduce(0, Integer::sum);
+    int numberOfSeats = constituency.numberOfSeats();
+    double initialElectionNumber = totalVotes / (double) numberOfSeats;
+
+    Map<Nomination, Long> assignedSeatsPerNomination = calculateAssignedSeatsPerNomination(
+        nominations, numberOfSeats, initialElectionNumber);
+
+    return ElectedResult.builder()
+        .electedCandidates(findElectedCandidates(assignedSeatsPerNomination))
+        .usedElectionNumbers(electionNumberHistory)
+        .build();
+  }
+
+  @NonNull
+  private Map<Nomination, Collection<Candidate>> findElectedCandidates(
+      @NonNull Map<Nomination, Long> assignedSeatsPerNomination) {
+
+    Map<Nomination, Collection<Candidate>> electedCandidates = new HashMap<>();
+    assignedSeatsPerNomination.entrySet().stream()
+        .filter(entry -> entry.getValue() > 0)
+        .forEach(entry ->
+            electedCandidates.put(entry.getKey(), findCandidates(entry.getKey(), entry.getValue())));
+
+    return electedCandidates;
+  }
+
+  @NonNull
+  private Collection<Candidate> findCandidates(@NonNull Nomination nomination, long numberOfSeats) {
+    List<Integer> positions = nomination.getVotingResult().getVotesPerPosition().entrySet().stream()
+        .sorted(Comparator.comparing(Entry<Integer, Integer>::getValue).reversed())
+        .map(Entry::getKey)
+        .toList();
+    Collection<Candidate> elected = new ArrayList<>();
+    for (int i = 0; i < numberOfSeats; i++) {
+      Integer position = positions.get(i);
+      elected.add(nomination.getCandidate(position));
+    }
+
+    return elected;
+  }
+
+  private Map<Nomination, Long> calculateAssignedSeatsPerNomination(
+      @NonNull Collection<Nomination> nominations,
+      int numberOfSeats, Double initialElectionNumber) {
+
+    double electionNumber = initialElectionNumber;
+    long assignedSeats;
+    Map<Nomination, Long> assignedSeatsPerNomination;
+
+    do {
+      electionNumberHistory.add(electionNumber);
+      Map<Nomination, Double> seatsPerNomination = new HashMap<>();
+      for (Nomination nomination : nominations) {
+        double seatNumber = calculateAssignedSeatNumber(electionNumber,
+            nomination.getVotingResult().getTotalVotes());
+        seatsPerNomination.put(nomination, seatNumber);
+      }
+      assignedSeatsPerNomination = seatsPerNomination.entrySet().stream()
+          .map(entry -> Map.entry(entry.getKey(), Math.round(entry.getValue())))
+          .collect(Collectors.toMap(Entry::getKey, Entry::getValue));
+      assignedSeats = assignedSeatsPerNomination.values().stream().reduce(0L, Long::sum);
+
+      if (assignedSeats < numberOfSeats) {
+        // election number was too big, decrease
+        electionNumber = calculateLowerElectionNumber(initialElectionNumber, seatsPerNomination,
+            assignedSeatsPerNomination);
+      } else if (assignedSeats > numberOfSeats) {
+        // election number was too small, increase
+        electionNumber = calculateHigherElectionNumber(initialElectionNumber, seatsPerNomination,
+            assignedSeatsPerNomination);
+      }
+    } while (assignedSeats != numberOfSeats);
+
+
+    return assignedSeatsPerNomination;
+  }
+
+  private static double calculateHigherElectionNumber(Double initialElectionNumber,
+      @NonNull Map<Nomination, Double> seatsPerNomination,
+      Map<Nomination, Long> assignedSeatsPerNomination) {
+    double electionNumber;
+    electionNumber = seatsPerNomination.entrySet().stream()
+        .map(entry -> Map.entry(entry.getKey(),
+            entry.getValue() - assignedSeatsPerNomination.get(entry.getKey())))
+        .min(Comparator.comparing(Entry<Nomination, Double>::getValue))
+        .map(entry -> entry.getKey().getVotingResult().getTotalVotes()
+            / (assignedSeatsPerNomination.get(entry.getKey()) - 0.5))
+        .orElse(initialElectionNumber);
+    return electionNumber;
+  }
+
+  private static double calculateLowerElectionNumber(Double initialElectionNumber,
+      @NonNull Map<Nomination, Double> seatsPerNomination,
+      Map<Nomination, Long> assignedSeatsPerNomination) {
+    double electionNumber;
+    electionNumber = seatsPerNomination.entrySet().stream()
+        .map(entry -> Map.entry(entry.getKey(),
+            entry.getValue() - assignedSeatsPerNomination.get(entry.getKey())))
+        .max(Comparator.comparing(Entry<Nomination, Double>::getValue))
+        .map(entry -> entry.getKey().getVotingResult().getTotalVotes()
+            / (assignedSeatsPerNomination.get(entry.getKey()) + 0.5))
+        .orElse(initialElectionNumber);
+    return electionNumber;
+  }
+
+
+
+  private double calculateAssignedSeatNumber(double electionNumber, int totalVotesOfNomination) {
+    return totalVotesOfNomination / electionNumber;
+  }
+}
@@ -0,0 +1,152 @@
+package de.twomartens.wahlrecht.service;
+
+import de.twomartens.wahlrecht.model.Candidate;
+import de.twomartens.wahlrecht.model.Constituency;
+import de.twomartens.wahlrecht.model.ElectedResult;
+import de.twomartens.wahlrecht.model.Nomination;
+import de.twomartens.wahlrecht.model.VotingResult;
+import java.util.Collection;
+import java.util.List;
+import java.util.Map;
+import org.assertj.core.api.Assertions;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+class ConstituencyCalculationServiceTest {
+  private static final Nomination SPD_NIENDORF = buildNomination("SPD-Niendorf");
+  private static final Nomination CDU_NIENDORF = buildNomination("CDU-Niendorf");
+  private static final Nomination FDP_NIENDORF = buildNomination("FDP-Niendorf");
+  private static final Nomination LINKE_NIENDORF = buildNomination("LINKE-Niendorf");
+  private static final Nomination GRUENE_NIENDORF = buildNomination("GRUENE-Niendorf");
+  private static final Nomination AFD_NIENDORF = buildNomination("AFD-Niendorf");
+
+  private ConstituencyCalculationService service;
+
+  @BeforeEach
+  void setService() {
+    service = new ConstituencyCalculationService();
+  }
+
+  @Test
+  void shouldCalculateConstituencyCorrectly() {
+    Constituency constituency = new Constituency("Niendorf", 5);
+    Collection<Nomination> nominations = List.of(
+        SPD_NIENDORF,
+        CDU_NIENDORF,
+        LINKE_NIENDORF,
+        FDP_NIENDORF,
+        GRUENE_NIENDORF,
+        AFD_NIENDORF
+    );
+    setUpCandidates();
+    setUpResults();
+
+    ElectedResult elected = service.calculateConstituency(constituency, nominations);
+
+    Assertions.assertThat(elected.electedCandidates())
+        .containsKey(SPD_NIENDORF)
+        .containsKey(CDU_NIENDORF)
+        .containsKey(GRUENE_NIENDORF)
+        .doesNotContainKey(LINKE_NIENDORF)
+        .doesNotContainKey(AFD_NIENDORF)
+        .doesNotContainKey(FDP_NIENDORF);
+  }
+
+  private void setUpCandidates() {
+    SPD_NIENDORF.addCandidates(new Candidate("Schwarzarius, Ines", ""));
+    SPD_NIENDORF.addCandidates(new Candidate("Urbanski, Torge", ""));
+    SPD_NIENDORF.addCandidates(new Candidate("Fischbach-Pyttel, Carola", ""));
+    SPD_NIENDORF.addCandidates(new Candidate("Bäcker, Guido", ""));
+    SPD_NIENDORF.addCandidates(new Candidate("Porr, Ulrike", ""));
+    SPD_NIENDORF.addCandidates(new Candidate("Petersen, Johannes", ""));
+    SPD_NIENDORF.addCandidates(new Candidate("Kröger, Manuela-Andrea", ""));
+    SPD_NIENDORF.addCandidates(new Candidate("Steppat, Wolfgang", ""));
+    SPD_NIENDORF.addCandidates(new Candidate("Canbay, Berfin", ""));
+    SPD_NIENDORF.addCandidates(new Candidate("Schumacher, Wolfgang", ""));
+
+    CDU_NIENDORF.addCandidates(new Candidate("Kuhn, Rüdiger", ""));
+    CDU_NIENDORF.addCandidates(new Candidate("Ahrens, Mareike", ""));
+    CDU_NIENDORF.addCandidates(new Candidate("Wysocki, Michael", ""));
+    CDU_NIENDORF.addCandidates(new Candidate("Dönselmann, Malte", ""));
+    CDU_NIENDORF.addCandidates(new Candidate("Seehaber, Daniel", ""));
+
+    LINKE_NIENDORF.addCandidates(new Candidate("Dr. Khenkhar, Malik", ""));
+    LINKE_NIENDORF.addCandidates(new Candidate("Radom, Claudia", ""));
+    LINKE_NIENDORF.addCandidates(new Candidate("Kara, Başak", ""));
+
+    FDP_NIENDORF.addCandidates(new Candidate("Häffs, Marvin", ""));
+    FDP_NIENDORF.addCandidates(new Candidate("Bahmer, Larissa", ""));
+    FDP_NIENDORF.addCandidates(new Candidate("Patzer, Heinrich-Otto", ""));
+
+    GRUENE_NIENDORF.addCandidates(new Candidate("Demirhan, Sina", ""));
+    GRUENE_NIENDORF.addCandidates(new Candidate("Schmidt, Lutz", "Redakteur"));
+
+    AFD_NIENDORF.addCandidates(new Candidate("Hanssen, Wolfgang", ""));
+  }
+
+  private void setUpResults() {
+    SPD_NIENDORF.setVotingResult(VotingResult.builder()
+        .votesOnNomination(0)
+        .votesPerPosition(Map.of(
+            1, 11882,
+            2, 7617,
+            3, 1946,
+            4, 1743,
+            5, 1363,
+            6, 762,
+            7, 895,
+            8, 1598,
+            9, 1786,
+            10, 781
+        ))
+        .build());
+
+    CDU_NIENDORF.setVotingResult(VotingResult.builder()
+        .votesOnNomination(0)
+        .votesPerPosition(Map.of(
+            1, 10733,
+            2, 4550,
+            3, 2310,
+            4, 2333,
+            5, 2565
+        ))
+        .build());
+
+    LINKE_NIENDORF.setVotingResult(VotingResult.builder()
+        .votesOnNomination(0)
+        .votesPerPosition(Map.of(
+            1, 3782,
+            2, 1584,
+            3, 1185
+        ))
+        .build());
+
+    FDP_NIENDORF.setVotingResult(VotingResult.builder()
+        .votesOnNomination(0)
+        .votesPerPosition(Map.of(
+            1, 2498,
+            2, 3200,
+            3, 992
+        ))
+        .build());
+
+    GRUENE_NIENDORF.setVotingResult(VotingResult.builder()
+        .votesOnNomination(0)
+        .votesPerPosition(Map.of(
+            1, 14838,
+            2, 12501
+        ))
+        .build());
+
+    AFD_NIENDORF.setVotingResult(VotingResult.builder()
+        .votesOnNomination(0)
+        .votesPerPosition(Map.of(
+            1, 6616
+        ))
+        .build());
+  }
+
+  private static Nomination buildNomination(String name) {
+    return new Nomination(name, false);
+  }
+}