Add some fun stuff

.gitignore

@@ -0,0 +1,4 @@
+/ki_rwu_java.iml
+/.idea/
+/lib/
+/out/

README.md

@@ -0,0 +1,3 @@
+# KI_RWU
+
+This is a repository containing basic AI algorithms taught in the AI lecture at _Hochschule Ravensburg-Weingarten_.

src/machine_learning/Vector.java

@@ -34,7 +34,7 @@ public class Vector
 
     public Vector add(Vector b)
     {
-        if (this.dimension() != b.dimension()) throw new IllegalArgumentException("Dimensions must be equals.");
+        checkEqualDimensions(b);
         return new Vector(IntStream.range(0,
                 this.dimension())
                 .mapToObj(i -> this.get(i) + b.get(i))
@@ -45,7 +45,7 @@ public class Vector
 
     public Vector subtract(Vector b)
     {
-        if (this.dimension() != b.dimension()) throw new IllegalArgumentException("Dimensions must be equals.");
+        checkEqualDimensions(b);
         return new Vector(IntStream.range(0,
                 this.dimension())
                 .mapToObj(i -> this.get(i) - b.get(i))
@@ -55,7 +55,7 @@ public class Vector
 
     public double scalar(Vector b)
     {
-        if (this.dimension() != b.dimension()) throw new IllegalArgumentException("Dimensions must be equals.");
+        checkEqualDimensions(b);
         return IntStream.range(0,
                 this.dimension())
                 .mapToDouble(i -> this.get(i) * b.get(i))
@@ -80,14 +80,9 @@ public class Vector
 
     public Vector divide(double div)
     {
-        var divided = new ArrayList<Double>();
+        return new Vector(IntStream.range(0, this.dimension())
-
+                .mapToObj(i -> this.values.get(i) / div)
-        for (int i = 0; i < this.dimension(); i++)
+                .collect(Collectors.toCollection(ArrayList::new)));
-        {
-            divided.add(this.values.get(i) / div);
-        }
-
-        return new Vector(divided);
     }
 
     public double get(int index)
@@ -133,4 +128,10 @@ public class Vector
     {
         return this.values.toString();
     }
+
+    private void checkEqualDimensions(Vector b)
+    {
+        if (this.dimension() != b.dimension())
+            throw new IllegalArgumentException("Dimensions must be equal");
+    }
 }

src/machine_learning/nearest_neighbour/DistanceFunction.java

@@ -2,7 +2,7 @@ package machine_learning.nearest_neighbour;
 
 import machine_learning.Vector;
 
-public interface Distance
+public interface DistanceFunction
 {
     double distance(Vector a, Vector b);
 }

src/machine_learning/nearest_neighbour/KNearestNeighbour.java

@@ -15,18 +15,18 @@ public class KNearestNeighbour implements MachineLearning
     private List<Vector> positives;
     private List<Vector> negatives;
 
-    private final Distance distance;
+    private final DistanceFunction distanceFunction;
 
     private final int k;
 
-    public KNearestNeighbour(Distance distance)
+    public KNearestNeighbour(DistanceFunction distanceFunction)
     {
-        this(distance, 1);
+        this(distanceFunction, 1);
     }
 
-    public KNearestNeighbour(Distance distance, int k)
+    public KNearestNeighbour(DistanceFunction distanceFunction, int k)
     {
-        this.distance = distance;
+        this.distanceFunction = distanceFunction;
         this.k = k;
     }
 
@@ -67,7 +67,7 @@ public class KNearestNeighbour implements MachineLearning
     private List<Vector> nearestNeighbours(List<Vector> vectors, Vector vector)
     {
         return vectors.parallelStream()
-                .map(v -> Map.entry(this.distance.distance(v, vector), v))
+                .map(v -> Map.entry(this.distanceFunction.distance(v, vector), v))
                 .sorted((e1, e2) -> e1.getKey() >= e2.getKey() ? (e1.getKey().equals(e2.getKey()) ? 0 : 1) : -1)
                 .map(Map.Entry::getValue)
                 .collect(Collectors.toList())

src/search/ChessKnightNode.java

@@ -0,0 +1,93 @@
+package search;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * For a Kata on codewars.com.
+ * How many moves need a knight (Springer) to get from a given start to a given end on the chessboard,
+ * e.g. a3 -> b5, the knight needs 1 move;
+ * a1 -> f1, the knight needs 3 moves
+ */
+public class ChessKnightNode extends Node<ChessKnightNode.KnightPair> {
+    public ChessKnightNode(final KnightPair state) {
+        super(state);
+    }
+
+    private ChessKnightNode(final KnightPair value, final Node<KnightPair> parent, final int heuristicCosts) {
+        super(value, parent, heuristicCosts);
+    }
+
+    @Override
+    public boolean isTargetReached(final Node<KnightPair> target) {
+        return this.valueEquals(target);
+    }
+
+    @Override
+    public List<Node<KnightPair>> generateSuccessors() {
+        final var successors = new ArrayList<Node<KnightPair>>();
+
+        for (final var dir : ChessDirections.values()) {
+            try {
+                final char newCol = (char) (super.value.col() + dir.getColChange());
+                final char newRow = (char) (super.value.row() + dir.getRowChange());
+
+                final var newState = new KnightPair(newCol, newRow);
+
+                final var successor = new ChessKnightNode(newState, this, super.heuristicCosts + 1);
+
+                if (!successor.valueEquals(this) && !successor.valueEquals(super.getParent())) {
+                    successors.add(successor);
+                }
+            } catch (final ChessKnightException ignored) {
+            }
+        }
+
+        return successors;
+    }
+
+    private boolean valueEquals(final Node<KnightPair> node) {
+        return node != null && super.value.equals(node.value);
+    }
+
+    @Override
+    public String toString() {
+        return "%c%c".formatted(super.value.col, super.value.row);
+    }
+
+    protected record KnightPair(char col, char row) {
+        public KnightPair {
+            if (col < 'a' || col > 'h') throw new ChessKnightException("Row out of bounds at index %c".formatted(col));
+            if (row < '1' || row > '8') throw new ChessKnightException("Column out of bounds at index %c".formatted(row));
+        }
+    }
+
+    protected enum ChessDirections {
+        TOP_LEFT(-1, 2), TOP_RIGHT(1, 2),
+        RIGHT_TOP(2, 1), RIGHT_BOTTOM(2, -1),
+        DOWN_RIGHT(1 ,-2), DOWN_LEFT(-1,-2),
+        LEFT_BOTTOM(-2,-1), LEFT_TOP(-2,1);
+
+        public final int colChange;
+        public final int rowChange;
+
+        ChessDirections( final int colChange, final int rowChange) {
+            this.colChange = colChange;
+            this.rowChange = rowChange;
+        }
+
+        public int getColChange() {
+            return colChange;
+        }
+
+        public int getRowChange() {
+            return rowChange;
+        }
+    }
+
+    protected static class ChessKnightException extends IndexOutOfBoundsException {
+        public ChessKnightException(final String s) {
+            super(s);
+        }
+    }
+}

test/machine_learning/nearest_neighbour/KNearestNeighbourTest.java

@@ -3,6 +3,7 @@ package machine_learning.nearest_neighbour;
 import machine_learning.DataClass;
 import machine_learning.Vector;
 import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.TestInstance;
 import org.opentest4j.AssertionFailedError;
@@ -22,8 +23,9 @@ import static org.junit.jupiter.api.Assertions.*;
 @TestInstance(TestInstance.Lifecycle.PER_CLASS)
 class KNearestNeighbourTest
 {
-    List<Vector> positives;
+    private List<Vector> positives;
-    List<Vector> negatives;
+    private List<Vector> negatives;
+    private DistanceFunction distanceFunction;
 
     @BeforeAll
     void initLearnData()
@@ -41,12 +43,14 @@ class KNearestNeighbourTest
                 new Vector(8d, 2d),
                 new Vector(9d, 0d))
         );
+
+        this.distanceFunction = (a, b) -> Math.abs(a.get(0) - b.get(0)) + Math.abs(a.get(1) - b.get(1));
     }
 
     @Test
     public void shouldReturnCorrectClassForVectorWithKEquals3()
     {
-        var kNearestNeighbour = new KNearestNeighbour((a ,b) -> Math.abs(a.get(0) - b.get(0)) + Math.abs(a.get(1) - b.get(1)), 3);
+        var kNearestNeighbour = new KNearestNeighbour(this.distanceFunction, 3);
         kNearestNeighbour.learn(this.positives, this.negatives);
         var vector = new Vector(8, 3.5);
 
@@ -59,7 +63,7 @@ class KNearestNeighbourTest
     @Test
     public void shouldReturnCorrectClassForVectorWithKEquals5()
     {
-        var kNearestNeighbour = new KNearestNeighbour((a ,b) -> Math.abs(a.get(0) - b.get(0)) + Math.abs(a.get(1) - b.get(1)), 5);
+        var kNearestNeighbour = new KNearestNeighbour(this.distanceFunction, 5);
         kNearestNeighbour.learn(this.positives, this.negatives);
         var vector = new Vector(8, 3.5);
 
@@ -110,6 +114,7 @@ class KNearestNeighbourTest
 
     }
 
+    @Disabled("Takes long")
     @Test
     public void shouldReturnOptimum()
     {

test/machine_learning/perceptron/PerceptronTest.java

@@ -1,16 +1,12 @@
 package machine_learning.perceptron;
 
-import machine_learning.Vector;
 import machine_learning.DataClass;
-import org.junit.jupiter.api.BeforeAll;
+import machine_learning.Vector;
-import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.*;
-import org.junit.jupiter.api.TestInstance;
 
 import java.util.ArrayList;
 import java.util.List;
 
-import static org.junit.jupiter.api.Assertions.*;
-
 @TestInstance(TestInstance.Lifecycle.PER_CLASS)
 class PerceptronTest
 {
@@ -48,7 +44,7 @@ class PerceptronTest
         var actualClass = this.perceptron.classify(vector);
         var expectedClass = DataClass.NEGATIVE;
 
-        assertEquals(expectedClass, actualClass);
+        Assertions.assertEquals(expectedClass, actualClass);
     }
 
     @Test
@@ -59,6 +55,6 @@ class PerceptronTest
         var actualClass = this.perceptron.classify(vector);
         var expectedClass = DataClass.POSITIVE;
 
-        assertEquals(expectedClass, actualClass);
+        Assertions.assertEquals(expectedClass, actualClass);
     }
 }

test/search/ChessKnightNodeTest.java

@@ -0,0 +1,107 @@
+package search;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+public class ChessKnightNodeTest
+{
+    @Test
+    public void shouldReturnTrueWhenTargetReached()
+    {
+        final var state = new ChessKnightNode.KnightPair('a', '1');
+
+        final var node = new ChessKnightNode(state);
+        final var target = new ChessKnightNode(state);
+
+        Assertions.assertTrue(node.isTargetReached(target));
+    }
+
+    @Test
+    public void shouldReturnFalseWhenTargetNotReached()
+    {
+        final var actualState = new ChessKnightNode.KnightPair('a', '1');
+
+        final var targetState = new ChessKnightNode.KnightPair('h', '8');
+
+        final var node = new ChessKnightNode(actualState);
+        final var target = new ChessKnightNode(targetState);
+
+        Assertions.assertFalse(node.isTargetReached(target));
+    }
+
+    @Test
+    public void shouldReturnNonEmptyListOfSuccessors()
+    {
+        final var state = new ChessKnightNode.KnightPair('a', '1');
+
+        final var node = new ChessKnightNode(state);
+        final var successors = node.generateSuccessors();
+
+        Assertions.assertFalse(successors.isEmpty());
+    }
+
+    @Test
+    public void shouldReturnCorrectSuccessorsWithMaxPossibleSuccessors()
+    {
+        final var state = new ChessKnightNode.KnightPair('f', '3');
+
+        final var node = new ChessKnightNode(state);
+        final var successors = node.generateSuccessors();
+
+        Assertions.assertEquals(8, successors.size());
+
+        final var newState1 = new ChessKnightNode.KnightPair('e', '5');
+        final var newState2 = new ChessKnightNode.KnightPair('g', '5');
+        final var newState3 = new ChessKnightNode.KnightPair('h', '4');
+        final var newState4 = new ChessKnightNode.KnightPair('h', '2');
+        final var newState5 = new ChessKnightNode.KnightPair('g', '1');
+        final var newState6 = new ChessKnightNode.KnightPair('e', '1');
+        final var newState7 = new ChessKnightNode.KnightPair('d', '2');
+        final var newState8 = new ChessKnightNode.KnightPair('d', '4');
+
+
+        Assertions.assertEquals(newState1, successors.get(0).getValue());
+        Assertions.assertEquals(newState2, successors.get(1).getValue());
+        Assertions.assertEquals(newState3, successors.get(2).getValue());
+        Assertions.assertEquals(newState4, successors.get(3).getValue());
+        Assertions.assertEquals(newState5, successors.get(4).getValue());
+        Assertions.assertEquals(newState6, successors.get(5).getValue());
+        Assertions.assertEquals(newState7, successors.get(6).getValue());
+        Assertions.assertEquals(newState8, successors.get(7).getValue());
+    }
+
+    @Test
+    public void shouldReturnCorrectSuccessorsOnEdge()
+    {
+        final var state = new ChessKnightNode.KnightPair('a', '1');
+
+        final var node = new ChessKnightNode(state);
+        final var successors = node.generateSuccessors();
+
+        Assertions.assertEquals(2, successors.size());
+
+        Assertions.assertThrows(ChessKnightNode.ChessKnightException.class,
+                () -> new ChessKnightNode.KnightPair((char) ('a' - 1), '3'));
+
+        final var newState1 = new ChessKnightNode.KnightPair('b', '3');
+        final var newState2 = new ChessKnightNode.KnightPair('c', '2');
+
+        Assertions.assertThrows(ChessKnightNode.ChessKnightException.class,
+                () -> new ChessKnightNode.KnightPair('c', '0'));
+
+        Assertions.assertThrows(ChessKnightNode.ChessKnightException.class,
+                () -> new ChessKnightNode.KnightPair('c', (char) ('0' - 1)));
+
+        Assertions.assertThrows(ChessKnightNode.ChessKnightException.class,
+                () -> new ChessKnightNode.KnightPair((char) ('a' - 1), (char) ('0' - 1)));
+
+        Assertions.assertThrows(ChessKnightNode.ChessKnightException.class,
+                () -> new ChessKnightNode.KnightPair((char) ('a' - 2), '0'));
+
+        Assertions.assertThrows(ChessKnightNode.ChessKnightException.class,
+                () -> new ChessKnightNode.KnightPair((char) ('a' - 2), '3'));
+
+        Assertions.assertEquals(newState1, successors.get(0).getValue());
+        Assertions.assertEquals(newState2, successors.get(1).getValue());
+    }
+}

test/search/ChessKnightTest.java

@@ -0,0 +1,51 @@
+package search;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+import search.uninformed.breadthfirstsearch.BreadthFirstSearch;
+
+import java.util.List;
+
+import static search.SearchTestUtils.countNodes;
+import static search.SearchTestUtils.printSolution;
+
+public class ChessKnightTest
+{
+    @Test
+    public void shouldReturnOne()
+    {
+        final var state = new ChessKnightNode.KnightPair('a', '3');
+
+        final var root = new ChessKnightNode(state);
+
+        final var targetState = new ChessKnightNode.KnightPair('b', '5');
+        final var expected = new ChessKnightNode(targetState);
+
+        final var actual = new BreadthFirstSearch().breadthFirstSearch(List.of(root), expected);
+
+        printSolution(actual);
+        var nodeCount = countNodes(actual);
+        var edgeCount = nodeCount - 1;
+
+        Assertions.assertEquals(1, edgeCount);
+    }
+
+    @Test
+    public void shouldReturnThree()
+    {
+        final var state = new ChessKnightNode.KnightPair('a', '1');
+
+        final var root = new ChessKnightNode(state);
+
+        final var targetState = new ChessKnightNode.KnightPair('f', '1');
+        final var expected = new ChessKnightNode(targetState);
+
+        final var actual = new BreadthFirstSearch().breadthFirstSearch(List.of(root), expected);
+
+        printSolution(actual);
+        var nodeCount = countNodes(actual);
+        var edgeCount = nodeCount - 1;
+
+        Assertions.assertEquals(3, edgeCount);
+    }
+}

test/search/GameHelperTest.java

@@ -0,0 +1,77 @@
+package search;
+
+import org.junit.jupiter.api.Test;
+import search.uninformed.iterativedeepening.IterativeDeepening;
+
+import static search.SearchTestUtils.printSolution;
+
+public class GameHelperTest
+{
+    @Test
+    void shouldReturnCorrectTargetDemonologist()
+    {
+        final int[][] state = {
+                {8, 4 ,0},
+                {6, 3, 1},
+                {2, 5, 7}
+        };
+        final var root = new EightPuzzleNode(state);
+
+        final int[][] targetState = {
+                {1, 2, 3},
+                {4, 5, 6},
+                {7, 8, 0}
+        };
+        final var expected = new EightPuzzleNode(targetState);
+
+        final var actual = new IterativeDeepening().iterativeDeepening(root, expected);
+
+        printSolution(actual);
+    }
+
+    @Test
+    void shouldReturnCorrectTargetWartales()
+    {
+        final int[][] state = {
+                {1, 8, 6},
+                {3, 2, 7},
+                {5, 4, 0}
+        };
+        final var root = new EightPuzzleNode(state);
+
+        final int[][] targetState = {
+                {1, 2, 3},
+                {4, 5, 6},
+                {7, 8, 0}
+        };
+        final var expected = new EightPuzzleNode(targetState);
+
+        final var actual = new IterativeDeepening().iterativeDeepening(root, expected);
+
+        printSolution(actual);
+    }
+
+    @Test
+    void shouldReturnCorrectTargetLabyrinthine()
+    {
+        final boolean[][] state = {
+                {true, false, true},
+                {false, true, false},
+                {true, false, true}
+        };
+
+        final var root = new LabyrinthineNode(state);
+
+        final boolean[][] targetState = {
+                {true, true, true},
+                {true, true, true},
+                {true, true, true},
+        };
+
+        final var expected = new LabyrinthineNode(targetState);
+
+        final var actual = new IterativeDeepening().iterativeDeepening(root, expected);
+
+        printSolution(actual);
+    }
+}

test/search/SearchTestUtils.java

@@ -17,4 +17,18 @@ public class SearchTestUtils
 
         System.out.println("START");
     }
+
+    public static <T> int countNodes(final Node<T> targetNode)
+    {
+        var node = targetNode;
+
+        int nodeCount = 0;
+        while (node != null)
+        {
+            nodeCount++;
+            node = node.getParent();
+        }
+
+        return nodeCount;
+    }
 }

test/search/uninformed/iterativedeepening/IterativeDeepeningTest.java

@@ -51,28 +51,4 @@ class IterativeDeepeningTest
 
         printSolution(actual);
     }
-
-    @Test
-    void shouldReturnCorrectTargetLabyrinthine()
-    {
-        final boolean[][] state = {
-                {true, false, true},
-                {false, true, false},
-                {true, false, true}
-        };
-
-        final var root = new LabyrinthineNode(state);
-
-        final boolean[][] targetState = {
-                {true, true, true},
-                {true, true, true},
-                {true, true, true},
-        };
-
-        final var expected = new LabyrinthineNode(targetState);
-
-        final var actual = new IterativeDeepening().iterativeDeepening(root, expected);
-
-        printSolution(actual);
-    }
 }