Added Guava, refactored NumberPlateDetectorImpl

oskopek · Apr 18, 2014 · 01ec827 · 01ec827
1 parent 30578c2
commit 01ec827
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Showing 2 changed files with 28 additions and 38 deletions.
diff --git a/carcv-core/pom.xml b/carcv-core/pom.xml
@@ -100,6 +100,11 @@
             <artifactId>commons-lang</artifactId>
             <version>20030203.000129</version>
         </dependency>
+        <dependency>
+            <groupId>com.google.guava</groupId>
+            <artifactId>guava</artifactId>
+            <version>13.0.1</version>
+        </dependency>
         <dependency>
             <groupId>junit</groupId>
             <artifactId>junit</artifactId>

diff --git a/carcv-core/src/main/java/org/carcv/impl/core/detect/NumberPlateDetectorImpl.java b/carcv-core/src/main/java/org/carcv/impl/core/detect/NumberPlateDetectorImpl.java
@@ -18,14 +18,13 @@
 
 import java.io.IOException;
 import java.util.ArrayList;
-import java.util.Collections;
-import java.util.Comparator;
-import java.util.HashMap;
 import java.util.List;
-import java.util.Map.Entry;
 
 import javax.xml.parsers.ParserConfigurationException;
 
+import com.google.common.collect.Multiset;
+import com.google.common.collect.Multisets;
+import com.google.common.collect.TreeMultiset;
 import net.sf.javaanpr.imageanalysis.CarSnapshot;
 import net.sf.javaanpr.intelligence.Intelligence;
 
@@ -36,29 +35,38 @@
 import org.xml.sax.SAXException;
 
 /**
- * A Singleton implementation of <code>NumberPlateDetector</code> based on <a
+ * An implementation of <code>NumberPlateDetector</code> based on <a
  * href="https://github.com/oskopek/javaanpr.git">JavaANPR</a>.
  *
  * <p>
  * Make sure all images are loaded in advance!
- *
  */
 public class NumberPlateDetectorImpl extends NumberPlateDetector {
 
     final private static Logger LOGGER = LoggerFactory.getLogger(NumberPlateDetectorImpl.class);
 
-    private static NumberPlateDetectorImpl detector = new NumberPlateDetectorImpl();
-
-    private NumberPlateDetectorImpl() {
+    private static NumberPlateDetectorImpl detector;
+    private Intelligence intel;
 
+    public NumberPlateDetectorImpl() throws IllegalStateException {
+        try {
+            intel = new Intelligence();
+        } catch (ParserConfigurationException | SAXException | IOException e) {
+            IllegalStateException ise = new IllegalStateException("Error occurred while initializing detector");
+            ise.addSuppressed(e);
+            throw ise;
+        }
     }
 
     /**
      * Returns a reference to the static singleton instantiation of NumberPlateDetectorImpl
      *
-     * @return reference to static NumberPlateDetectorImpl instance
+     * @return reference to static NumberPlateDetectorImpl instance, null if an error occurs during initialization
      */
-    public static NumberPlateDetectorImpl getInstance() {
+    public static NumberPlateDetectorImpl getInstance() throws IllegalStateException {
+        if (detector == null) {
+            detector = new NumberPlateDetectorImpl();
+        }
         return detector;
     }
 
@@ -69,22 +77,10 @@ public String detect(final List<? extends AbstractCarImage> images) {
 
     @Override
     public String detectPlateText(final List<? extends AbstractCarImage> images) {
-
-        Intelligence intel;
-        try {
-            intel = new Intelligence();
-        } catch (ParserConfigurationException | SAXException | IOException e) {
-            LOGGER.error("Error occured while detecting plate text!");
-            e.printStackTrace();
-            return null;
-        }
-
         ArrayList<String> numberPlates = new ArrayList<>();
-
         for (AbstractCarImage image : images) {
             numberPlates.add(intel.recognize(new CarSnapshot(image.getImage())));
         }
-
         return getAverageNumberPlate(numberPlates);
     }
 
@@ -94,21 +90,10 @@ public String detectPlateOrigin(final List<? extends AbstractCarImage> images) {
     }
 
     private static String getAverageNumberPlate(final List<String> numberPlates) {
-        HashMap<String, Integer> map = new HashMap<>();
-
-        for (String s : numberPlates) {
-            Integer count = map.get(s);
-            map.put(s, count != null ? count + 1 : 0);
-        }
-
-        String popular = Collections.max(map.entrySet(), new Comparator<Entry<String, Integer>>() {
-
-            @Override
-            public int compare(Entry<String, Integer> o1, Entry<String, Integer> o2) {
-                return o1.getValue().compareTo(o2.getValue());
-            }
-        }).getKey();
-
+        final Multiset<String> plateSet = TreeMultiset.create();
+        plateSet.addAll(numberPlates);
+        String popular = Multisets.copyHighestCountFirst(plateSet).iterator().next();
+        LOGGER.debug("Most popular plate is {}, occurrences {}", popular, plateSet.count(popular));
         return popular;
     }
 }