[api] Fixes topK items for DetectedObjects and make it configurable t…

…o Classifications

Change-Id: I4ffd29cff5205f32ee18afa5269d70491634936e

api/src/main/java/ai/djl/modality/Classifications.java

@@ -45,6 +45,7 @@ public class Classifications implements JsonSerializable {
 
     protected List<String> classNames;
     protected List<Double> probabilities;
+    private int topK;
 
     /**
      * Constructs a {@code Classifications} using a parallel list of classNames and probabilities.
@@ -55,6 +56,7 @@ public class Classifications implements JsonSerializable {
     public Classifications(List<String> classNames, List<Double> probabilities) {
         this.classNames = classNames;
         this.probabilities = probabilities;
+        this.topK = 5;
     }
 
     /**
@@ -65,11 +67,33 @@ public Classifications(List<String> classNames, List<Double> probabilities) {
      * @param probabilities the probabilities for each class for the input
      */
     public Classifications(List<String> classNames, NDArray probabilities) {
+        this(classNames, probabilities, 5);
+    }
+
+    /**
+     * Constructs a {@code Classifications} using list of classNames parallel to an NDArray of
+     * probabilities.
+     *
+     * @param classNames the names of the classes
+     * @param probabilities the probabilities for each class for the input
+     * @param topK the number of top classes to return
+     */
+    public Classifications(List<String> classNames, NDArray probabilities, int topK) {
         this.classNames = classNames;
         NDArray array = probabilities.toType(DataType.FLOAT64, false);
         this.probabilities =
                 Arrays.stream(array.toDoubleArray()).boxed().collect(Collectors.toList());
         array.close();
+        this.topK = topK;
+    }
+
+    /**
+     * Set the topK number of classes to be displayed.
+     *
+     * @param topK the number of top classes to return
+     */
+    public final void setTopK(int topK) {
+        this.topK = topK;
     }
 
     /**
@@ -99,6 +123,16 @@ public <T extends Classification> T item(int index) {
         return (T) new Classification(classNames.get(index), probabilities.get(index));
     }
 
+    /**
+     * Returns a list of the top classes.
+     *
+     * @param <T> the type of the classification item for the task
+     * @return the list of classification items for the best classes in order of best to worst
+     */
+    public <T extends Classification> List<T> topK() {
+        return topK(topK);
+    }
+
     /**
      * Returns a list of the top {@code k} best classes.
      *
@@ -163,7 +197,7 @@ public ByteBuffer toByteBuffer() {
     public String toString() {
         StringBuilder sb = new StringBuilder();
         sb.append('[').append(System.lineSeparator());
-        for (Classification item : topK(5)) {
+        for (Classification item : topK(topK)) {
             sb.append('\t').append(item).append(System.lineSeparator());
         }
         sb.append(']');
@@ -227,7 +261,7 @@ public static final class ClassificationsSerializer implements JsonSerializer<Cl
         /** {@inheritDoc} */
         @Override
         public JsonElement serialize(Classifications src, Type type, JsonSerializationContext ctx) {
-            List<?> list = src.topK(5);
+            List<?> list = src.topK();
             return ctx.serialize(list);
         }
     }

api/src/main/java/ai/djl/modality/cv/output/DetectedObjects.java

@@ -45,6 +45,7 @@ public DetectedObjects(
             List<String> classNames, List<Double> probabilities, List<BoundingBox> boundingBoxes) {
         super(classNames, probabilities);
         this.boundingBoxes = boundingBoxes;
+        setTopK(Integer.MAX_VALUE);
     }
 
     /** {@inheritDoc} */

api/src/main/java/ai/djl/modality/cv/translator/ImageClassificationTranslator.java

@@ -27,6 +27,7 @@ public class ImageClassificationTranslator extends BaseImageTranslator<Classific
 
     private SynsetLoader synsetLoader;
     private boolean applySoftmax;
+    private int topK;
 
     private List<String> classes;
 
@@ -39,6 +40,7 @@ public ImageClassificationTranslator(Builder builder) {
         super(builder);
         this.synsetLoader = builder.synsetLoader;
         this.applySoftmax = builder.applySoftmax;
+        this.topK = builder.topK;
     }
 
     /** {@inheritDoc} */
@@ -56,7 +58,7 @@ public Classifications processOutput(TranslatorContext ctx, NDList list) {
         if (applySoftmax) {
             probabilitiesNd = probabilitiesNd.softmax(0);
         }
-        return new Classifications(classes, probabilitiesNd);
+        return new Classifications(classes, probabilitiesNd, topK);
     }
 
     /**
@@ -85,9 +87,21 @@ public static Builder builder(Map<String, ?> arguments) {
     public static class Builder extends ClassificationBuilder<Builder> {
 
         private boolean applySoftmax;
+        private int topK = 5;
 
         Builder() {}
 
+        /**
+         * Set the topK number of classes to be displayed.
+         *
+         * @param topK the number of top classes to return
+         * @return the builder
+         */
+        public Builder optTopK(int topK) {
+            this.topK = topK;
+            return this;
+        }
+
         /**
          * Sets whether to apply softmax when processing output. Some models already include softmax
          * in the last layer, so don't apply softmax when processing model output.
@@ -111,6 +125,7 @@ protected Builder self() {
         protected void configPostProcess(Map<String, ?> arguments) {
             super.configPostProcess(arguments);
             applySoftmax = ArgumentsUtil.booleanValue(arguments, "applySoftmax");
+            topK = ArgumentsUtil.intValue(arguments, "topK", 5);
         }
 
         /**