#1704/#1705 weighted decision selection

core/src/main/java/com/scottlogic/datahelix/generator/core/profile/constraints/atomic/NotEqualToConstraint.java

@@ -48,7 +48,7 @@ public FieldSpec toFieldSpec() {
 
     @Override
     public String toString(){
-        return String.format("`%s` = %s", field.getName(), value);
+        return String.format("`%s` != %s", field.getName(), value);
     }
 
     @Override

core/src/main/java/com/scottlogic/datahelix/generator/core/walker/decisionbased/RowSpecTreeSolver.java

@@ -16,15 +16,16 @@
 package com.scottlogic.datahelix.generator.core.walker.decisionbased;
 
 import com.google.inject.Inject;
+import com.scottlogic.datahelix.generator.common.distribution.WeightedElement;
 import com.scottlogic.datahelix.generator.common.profile.Field;
 import com.scottlogic.datahelix.generator.common.profile.Fields;
-import com.scottlogic.datahelix.generator.core.fieldspecs.FieldSpecFactory;
+import com.scottlogic.datahelix.generator.common.profile.InSetRecord;
+import com.scottlogic.datahelix.generator.core.fieldspecs.*;
 import com.scottlogic.datahelix.generator.core.profile.constraints.atomic.AtomicConstraint;
 import com.scottlogic.datahelix.generator.core.decisiontree.ConstraintNode;
 import com.scottlogic.datahelix.generator.core.decisiontree.DecisionNode;
 import com.scottlogic.datahelix.generator.core.decisiontree.DecisionTree;
-import com.scottlogic.datahelix.generator.core.fieldspecs.FieldSpec;
-import com.scottlogic.datahelix.generator.core.fieldspecs.RowSpec;
+import com.scottlogic.datahelix.generator.core.profile.constraints.atomic.InSetConstraint;
 import com.scottlogic.datahelix.generator.core.reducer.ConstraintReducer;
 import com.scottlogic.datahelix.generator.core.walker.pruner.Merged;
 import com.scottlogic.datahelix.generator.core.walker.pruner.TreePruner;
@@ -51,45 +52,91 @@ public RowSpecTreeSolver(ConstraintReducer constraintReducer,
         this.optionPicker = optionPicker;
     }
 
-    public Stream<RowSpec> createRowSpecs(DecisionTree tree) {
+    public Stream<WeightedElement<RowSpec>> createRowSpecs(DecisionTree tree) {
         return flatMap(reduceToRowNodes(tree.rootNode),
             rootNode -> toRowspec(tree.fields, rootNode));
     }
 
-    private Stream<RowSpec> toRowspec(Fields fields, ConstraintNode rootNode) {
-        Optional<RowSpec> result = constraintReducer.reduceConstraintsToRowSpec(fields, rootNode);
-        return result.map(Stream::of).orElseGet(Stream::empty);
+    private Stream<WeightedElement<RowSpec>> toRowspec(Fields fields, WeightedElement<ConstraintNode> rootNode) {
+        Optional<RowSpec> result = constraintReducer.reduceConstraintsToRowSpec(fields, rootNode.element());
+        return result
+            .map(rowSpec -> new WeightedElement<>(rowSpec, rootNode.weight()))
+            .map(Stream::of)
+            .orElseGet(Stream::empty);
     }
 
     /**
      * a row node is a constraint node with no further decisions
      */
-    private Stream<ConstraintNode> reduceToRowNodes(ConstraintNode rootNode) {
-        if (rootNode.getDecisions().isEmpty()) {
+    private Stream<WeightedElement<ConstraintNode>> reduceToRowNodes(ConstraintNode rootNode) {
+        return reduceToRowNodes(new WeightedElement<>(rootNode, 1));
+    }
+
+    private Stream<WeightedElement<ConstraintNode>> reduceToRowNodes(WeightedElement<ConstraintNode> rootNode) {
+        if (rootNode.element().getDecisions().isEmpty()) {
             return Stream.of(rootNode);
         }
 
-        DecisionNode decisionNode = optionPicker.pickDecision(rootNode);
-        ConstraintNode rootWithoutDecision = rootNode.builder().removeDecision(decisionNode).build();
+        DecisionNode decisionNode = optionPicker.pickDecision(rootNode.element());
+        ConstraintNode rootWithoutDecision = rootNode.element().builder().removeDecision(decisionNode).build();
 
-        Stream<ConstraintNode> rootOnlyConstraintNodes = optionPicker.streamOptions(decisionNode)
+        Stream<WeightedElement<ConstraintNode>> rootOnlyConstraintNodes = optionPicker.streamOptions(decisionNode)
             .map(option -> combineWithRootNode(rootWithoutDecision, option))
-            .filter(newNode -> !newNode.isContradictory())
-            .map(Merged::get);
+            .filter(newNode -> !newNode.element().isContradictory())
+            .map(weighted -> new WeightedElement<>(weighted.element().get(), weighted.weight()));
 
         return flatMap(
             rootOnlyConstraintNodes,
-            this::reduceToRowNodes);
+            weightedConstraintNode -> reduceToRowNodes(
+                new WeightedElement<ConstraintNode>(
+                    weightedConstraintNode.element(),
+                    weightedConstraintNode.weight() / rootNode.weight())));
     }
 
-    private Merged<ConstraintNode> combineWithRootNode(ConstraintNode rootNode, ConstraintNode option) {
+    private WeightedElement<Merged<ConstraintNode>> combineWithRootNode(ConstraintNode rootNode, ConstraintNode option) {
         ConstraintNode constraintNode = rootNode.builder()
             .addDecisions(option.getDecisions())
             .addAtomicConstraints(option.getAtomicConstraints())
             .addRelations(option.getRelations())
             .build();
 
-        return treePruner.pruneConstraintNode(constraintNode, getFields(option));
+        double applicabilityOfThisOption = option.getAtomicConstraints().stream()
+            .mapToDouble(optionAtomicConstraint -> rootNode.getAtomicConstraints().stream()
+                .filter(rootAtomicConstraint -> rootAtomicConstraint.getField().equals(optionAtomicConstraint.getField()))
+                .filter(rootAtomicConstraint -> rootAtomicConstraint instanceof InSetConstraint)
+                .map(rootAtomicConstraint -> (InSetConstraint)rootAtomicConstraint)
+                .findFirst()
+                .map(matchingRootAtomicConstraint -> {
+                    double totalWeighting = matchingRootAtomicConstraint.legalValues.stream()
+                        .mapToDouble(InSetRecord::getWeightValueOrDefault).sum();
+
+                    double relevantWeighting = matchingRootAtomicConstraint.legalValues.stream()
+                        .filter(legalValue -> optionAtomicConstraint.toFieldSpec().canCombineWithLegalValue(legalValue.getElement()))
+                        .mapToDouble(InSetRecord::getWeightValueOrDefault).sum();
+
+                    return relevantWeighting / totalWeighting;
+                })
+                .orElse(1d))
+            .sum();
+
+        if (applicabilityOfThisOption > 1){
+            double applicabilityFraction = applicabilityOfThisOption - (int) applicabilityOfThisOption;
+            applicabilityOfThisOption = applicabilityFraction == 0
+                ? 1
+                : applicabilityFraction;
+        }
+
+        if (applicabilityOfThisOption == 0){
+            return new WeightedElement<>(
+                Merged.contradictory(),
+                1
+            );
+        }
+
+        return new WeightedElement<>(
+            treePruner.pruneConstraintNode(constraintNode, getFields(option)),
+            applicabilityOfThisOption
+        );
     }
 
     private Map<Field, FieldSpec> getFields(ConstraintNode option) {

core/src/main/java/com/scottlogic/datahelix/generator/core/walker/rowspec/RandomRowSpecDecisionTreeWalker.java

@@ -17,6 +17,7 @@
 package com.scottlogic.datahelix.generator.core.walker.rowspec;
 
 import com.google.inject.Inject;
+import com.scottlogic.datahelix.generator.common.distribution.WeightedElement;
 import com.scottlogic.datahelix.generator.core.decisiontree.DecisionTree;
 import com.scottlogic.datahelix.generator.core.fieldspecs.RowSpec;
 import com.scottlogic.datahelix.generator.core.generation.databags.DataBag;
@@ -59,7 +60,7 @@ public Stream<DataBag> walk(DecisionTree tree) {
     }
 
     private Stream<RowSpec> getFromCachedRowSpecs(DecisionTree tree) {
-        List<RowSpec> rowSpecCache = rowSpecTreeSolver.createRowSpecs(tree).collect(Collectors.toList());
+        List<WeightedElement<RowSpec>> rowSpecCache = rowSpecTreeSolver.createRowSpecs(tree).collect(Collectors.toList());
         return Stream.generate(() -> getRandomRowSpec(rowSpecCache));
     }
 
@@ -79,11 +80,46 @@ private Stream<RowSpec> getRowSpecAndRestart(DecisionTree tree) {
     }
 
     private Optional<RowSpec> getFirstRowSpec(DecisionTree tree) {
-        return rowSpecTreeSolver.createRowSpecs(tree).findFirst();
+        return rowSpecTreeSolver.createRowSpecs(tree).findFirst().map(WeightedElement::element);
     }
 
-    private RowSpec getRandomRowSpec(List<RowSpec> rowSpecCache) {
-        return rowSpecCache.get(random.nextInt(rowSpecCache.size()));
+    /**
+     * Get a row spec from the rowSpecCache in a weighted manner.<br />
+     * I.e. if there are 2 rowSpecs, one with a 70% weighting and the other with 30%.<br />
+     * Calling this method 10 times should *ROUGHLY* emit 7 of the 70% weighted rowSpecs and 3 of the others.<br />
+     * It does this by producing a virtual rowSpec 'range', i.e.<br />
+     *  - values between 1 and 70 represent the 70% weighted rowSpec<br />
+     *  - values between 71 and 100 represent the 30% weighted rowSpec<br />
+     * <br />
+     *  The function then picks a random number between 1 and 100 and yields the rowSpec that encapsulates that value.<br />
+     * <br />
+     *  As this method uses a random number generator, it will not ALWAYS yield a correct split, but it is more LIKELY than not.<br />
+     * @param rowSpecCache a list of weighted rowSpecs (weighting is between 0 and 1)
+     * @return a rowSpec picked from the list of weighted rowSpecs
+     */
+    private RowSpec getRandomRowSpec(List<WeightedElement<RowSpec>> rowSpecCache) {
+        double totalRange = rowSpecCache.stream()
+            .mapToDouble(WeightedElement::weight).sum();
+
+        double nextRowSpecFromRange = random.nextInt((int)(totalRange * 100)) / 100d;
+
+        double currentPosition = 0d;
+        WeightedElement<RowSpec> lastRowSpec = null;
+
+        for (WeightedElement<RowSpec> weightedRowSpec: rowSpecCache) {
+            double thisRowSpecRange = weightedRowSpec.weight();
+            double newPosition = thisRowSpecRange + currentPosition;
+
+            if (newPosition >= nextRowSpecFromRange)
+            {
+                return weightedRowSpec.element();
+            }
+
+            currentPosition = newPosition;
+            lastRowSpec = weightedRowSpec;
+        }
+
+        return lastRowSpec.element();
     }
 
     private DataBag createDataBag(RowSpec rowSpec) {

core/src/main/java/com/scottlogic/datahelix/generator/core/walker/rowspec/RowSpecDecisionTreeWalker.java

@@ -16,6 +16,7 @@
 package com.scottlogic.datahelix.generator.core.walker.rowspec;
 
 import com.google.inject.Inject;
+import com.scottlogic.datahelix.generator.common.distribution.WeightedElement;
 import com.scottlogic.datahelix.generator.common.util.FlatMappingSpliterator;
 import com.scottlogic.datahelix.generator.core.decisiontree.DecisionTree;
 import com.scottlogic.datahelix.generator.core.generation.databags.DataBag;
@@ -38,7 +39,7 @@ public RowSpecDecisionTreeWalker(RowSpecTreeSolver rowSpecTreeSolver, RowSpecDat
     @Override
     public Stream<DataBag> walk(DecisionTree tree) {
         return FlatMappingSpliterator.flatMap(
-            rowSpecTreeSolver.createRowSpecs(tree),
+            rowSpecTreeSolver.createRowSpecs(tree).map(WeightedElement::element),
             rowSpecDataBagGenerator::createDataBags);
     }
 }

core/src/test/java/com/scottlogic/datahelix/generator/core/builders/TestAtomicConstraintBuilder.java

@@ -26,6 +26,7 @@
 import java.util.List;
 import java.util.Set;
 import java.util.stream.Collectors;
+import java.util.stream.Stream;
 
 public class TestAtomicConstraintBuilder {
     private TestConstraintNodeBuilder testConstraintNodeBuilder;
@@ -56,6 +57,14 @@ public TestConstraintNodeBuilder isInSet(Object... legalValues) {
         return testConstraintNodeBuilder;
     }
 
+    public TestConstraintNodeBuilder isInSet(InSetRecord... weightedValues) {
+        InSetConstraint inSetConstraint = new InSetConstraint(
+            field,
+            Stream.of(weightedValues).collect(Collectors.toList()));
+        testConstraintNodeBuilder.constraints.add(inSetConstraint);
+        return testConstraintNodeBuilder;
+    }
+
     public TestConstraintNodeBuilder isNotInSet(Object... legalValues) {
         AtomicConstraint isInSetConstraint = new InSetConstraint(
             field,

core/src/test/java/com/scottlogic/datahelix/generator/core/decisiontree/RowSpecTreeSolverTests.java

@@ -16,6 +16,7 @@
 
 package com.scottlogic.datahelix.generator.core.decisiontree;
 
+import com.scottlogic.datahelix.generator.common.distribution.WeightedElement;
 import com.scottlogic.datahelix.generator.common.profile.Field;
 import com.scottlogic.datahelix.generator.common.profile.Fields;
 import com.scottlogic.datahelix.generator.common.profile.ProfileFields;
@@ -32,7 +33,6 @@
 import com.scottlogic.datahelix.generator.core.walker.decisionbased.RowSpecTreeSolver;
 import com.scottlogic.datahelix.generator.core.walker.decisionbased.SequentialOptionPicker;
 import com.scottlogic.datahelix.generator.core.walker.pruner.TreePruner;
-import org.junit.Assert;
 import org.junit.jupiter.api.Test;
 
 import java.util.ArrayList;
@@ -47,6 +47,7 @@
 import static org.mockito.Matchers.any;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;
+import static com.shazam.shazamcrest.MatcherAssert.assertThat;
 
 class RowSpecTreeSolverTests {
     private final FieldSpecMerger fieldSpecMerger = new FieldSpecMerger();
@@ -115,9 +116,10 @@ void test()
 
         final List<RowSpec> rowSpecs = dTreeWalker
             .createRowSpecs(merged)
+            .map(WeightedElement::element)
             .collect(Collectors.toList());
 
-        Assert.assertThat(rowSpecs, notNullValue());
+        assertThat(rowSpecs, notNullValue());
     }
 
 }