Initial commit

src/main/java/domain/jenetics/SpringsteenProblem.java

@@ -0,0 +1,83 @@
+package domain.jenetics;
+
+import io.jenetics.BitGene;
+import io.jenetics.engine.*;
+import io.jenetics.util.ISeq;
+
+import static java.util.Objects.requireNonNull;
+
+import java.util.function.Function;
+import java.util.stream.Collectors;
+
+
+public class SpringsteenProblem implements Problem<ISeq<SpringsteenRecord>, BitGene, Double> {
+
+    private ISeq<SpringsteenRecord> records;
+    private double maxPricePerUniqueSong;
+
+    public SpringsteenProblem(ISeq<SpringsteenRecord> records, double maxPricePerUniqueSong) {
+        this.records = requireNonNull(records);
+        this.maxPricePerUniqueSong = maxPricePerUniqueSong;
+    }
+
+    @Override
+    public Function<ISeq<SpringsteenRecord>, Double> fitness() {
+        return SpringsteenRecords -> {
+            double cost = SpringsteenRecords.stream()
+                .mapToDouble(r -> r.price)
+                .sum();
+
+            int uniqueSongCount = SpringsteenRecords.stream()
+                .flatMap(r -> r.songs.stream())
+                .collect(Collectors.toSet())
+                .size();
+
+            double pricePerUniqueSong = cost / uniqueSongCount;
+
+            return pricePerUniqueSong <= maxPricePerUniqueSong ? uniqueSongCount : 0.0;
+        };
+    }
+
+    @Override
+    public Codec<ISeq<SpringsteenRecord>, BitGene> codec() {
+        return Codecs.ofSubSet(records);
+    }
+
+    public static void main(String[] args) {
+        double maxPricePerUniqueSong = 2.5;
+
+        SpringsteenProblem springsteen = new SpringsteenProblem(
+            ISeq.of(new SpringsteenRecord("SpringsteenRecord1", 25, ISeq.of("Song1", "Song2", "Song3", "Song4", "Song5", "Song6")), new SpringsteenRecord("SpringsteenRecord2", 15, ISeq.of("Song2", "Song3", "Song4", "Song5", "Song6", "Song7")),
+                new SpringsteenRecord("SpringsteenRecord3", 35, ISeq.of("Song5", "Song6", "Song7", "Song8", "Song9", "Song10")), new SpringsteenRecord("SpringsteenRecord4", 17, ISeq.of("Song9", "Song10", "Song12", "Song4", "Song13", "Song14")),
+                new SpringsteenRecord("SpringsteenRecord5", 29, ISeq.of("Song1", "Song2", "Song13", "Song14", "Song15", "Song16")), new SpringsteenRecord("SpringsteenRecord6", 5, ISeq.of("Song18", "Song20", "Song30", "Song40"))),
+            maxPricePerUniqueSong);
+
+        Engine<BitGene, Double> engine = Engine.builder(springsteen)
+            .build();
+
+        ISeq<SpringsteenRecord> result = springsteen.codec()
+            .decoder()
+            .apply(engine.stream()
+                .limit(10)
+                .collect(EvolutionResult.toBestGenotype()));
+
+        double cost = result.stream()
+            .mapToDouble(r -> r.price)
+            .sum();
+
+        int uniqueSongCount = result.stream()
+            .flatMap(r -> r.songs.stream())
+            .collect(Collectors.toSet())
+            .size();
+
+        double pricePerUniqueSong = cost / uniqueSongCount;
+
+        System.out.println("Overall cost:  " + cost);
+        System.out.println("Unique songs:  " + uniqueSongCount);
+        System.out.println("Cost per song: " + pricePerUniqueSong);
+        System.out.println("Records:       " + result.map(r -> r.name)
+            .toString(", "));
+
+    }
+
+}