Create interface for Datamodel. First step for issues #83, #107, #108 ,

#109

rival-core/src/main/java/net/recommenders/rival/core/DataModel.java

@@ -30,25 +30,21 @@
  * @param <U> generic type for users
  * @param <I> generic type for items
  */
-public class DataModel<U, I> {
+public class DataModel<U, I> implements DataModelIF<U, I> {
 
     /**
      * Preference map between users and items.
      */
-    private Map<U, Map<I, Double>> userItemPreferences;
+    protected Map<U, Map<I, Double>> userItemPreferences;
     /**
-     * Preference map between items and users.
+     * Set containing all the items.
      */
-    private Map<I, Map<U, Double>> itemUserPreferences;
-    /**
-     * The map with the timestamps between users and items.
-     */
-    private Map<U, Map<I, Set<Long>>> userItemTimestamps;
+    protected Set<I> items;
     /**
      * Flag to indicate if duplicate preferences should be ignored or not.
      * Default: false.
      */
-    private boolean ignoreDuplicatePreferences;
+    protected boolean ignoreDuplicatePreferences;
 
     /**
      * Default constructor.
@@ -64,7 +60,7 @@ public DataModel() {
      * should be ignored.
      */
     public DataModel(final boolean ignoreDupPreferences) {
-        this(ignoreDupPreferences, new HashMap<U, Map<I, Double>>(), new HashMap<I, Map<U, Double>>(), new HashMap<U, Map<I, Set<Long>>>());
+        this(ignoreDupPreferences, new HashMap<U, Map<I, Double>>(), new HashSet<I>());
     }
 
     /**
@@ -73,52 +69,32 @@ public DataModel(final boolean ignoreDupPreferences) {
      * @param ignoreDupPreferences The flag to indicate whether preferences
      * should be ignored.
      * @param userItemPreference The preference map between users and items.
-     * @param itemUserPreference The preference map between items and users.
-     * @param userItemTimestamp The map with the timestamps between users and
-     * items
+     * @param itemSet The items.
      */
-    public DataModel(final boolean ignoreDupPreferences, final Map<U, Map<I, Double>> userItemPreference, final Map<I, Map<U, Double>> itemUserPreference,
-            final Map<U, Map<I, Set<Long>>> userItemTimestamp) {
+    public DataModel(final boolean ignoreDupPreferences, final Map<U, Map<I, Double>> userItemPreference, final Set<I> itemSet) {
         this.ignoreDuplicatePreferences = ignoreDupPreferences;
         this.userItemPreferences = userItemPreference;
-        this.itemUserPreferences = itemUserPreference;
-        this.userItemTimestamps = userItemTimestamp;
-    }
-
-    /**
-     * Method that returns the preference map between items and users.
-     *
-     * @return the preference map between items and users.
-     */
-    public Map<I, Map<U, Double>> getItemUserPreferences() {
-        return itemUserPreferences;
+        this.items = itemSet;
     }
 
     /**
      * Method that returns the preference map between users and items.
      *
      * @return the preference map between users and items.
      */
+    @Override
     public Map<U, Map<I, Double>> getUserItemPreferences() {
         return userItemPreferences;
     }
 
-    /**
-     * Method that returns the map with the timestamps between users and items.
-     *
-     * @return the map with the timestamps between users and items.
-     */
-    public Map<U, Map<I, Set<Long>>> getUserItemTimestamps() {
-        return userItemTimestamps;
-    }
-
     /**
      * Method that adds a preference to the model between a user and an item.
      *
      * @param u the user.
      * @param i the item.
      * @param d the preference.
      */
+    @Override
     public void addPreference(final U u, final I i, final Double d) {
         // update direct map
         Map<I, Double> userPreferences = userItemPreferences.get(u);
@@ -136,51 +112,27 @@ public void addPreference(final U u, final I i, final Double d) {
         if (preference != null) {
             preference += d;
             userPreferences.put(i, preference);
-            // update inverse map
-            Map<U, Double> itemPreferences = itemUserPreferences.get(i);
-            if (itemPreferences == null) {
-                itemPreferences = new HashMap<>();
-                itemUserPreferences.put(i, itemPreferences);
-            }
-            itemPreferences.put(u, preference);
-        }
-    }
-
-    /**
-     * Method that adds a timestamp to the model between a user and an item.
-     *
-     * @param u the user.
-     * @param i the item.
-     * @param t the timestamp.
-     */
-    public void addTimestamp(final U u, final I i, final Long t) {
-        Map<I, Set<Long>> userTimestamps = userItemTimestamps.get(u);
-        if (userTimestamps == null) {
-            userTimestamps = new HashMap<>();
-            userItemTimestamps.put(u, userTimestamps);
-        }
-        Set<Long> timestamps = userTimestamps.get(i);
-        if (timestamps == null) {
-            timestamps = new HashSet<>();
-            userTimestamps.put(i, timestamps);
         }
-        timestamps.add(t);
+        // update items
+        items.add(i);
     }
 
     /**
      * Method that returns the items in the model.
      *
      * @return the items in the model.
      */
+    @Override
     public Set<I> getItems() {
-        return getItemUserPreferences().keySet();
+        return items;
     }
 
     /**
      * Method that returns the users in the model.
      *
      * @return the users in the model.
      */
+    @Override
     public Set<U> getUsers() {
         return getUserItemPreferences().keySet();
     }
@@ -190,25 +142,27 @@ public Set<U> getUsers() {
      *
      * @return the number of items in the model.
      */
+    @Override
     public int getNumItems() {
-        return getItems().size();
+        return items.size();
     }
 
     /**
      * Method that returns the number of users in the model.
      *
      * @return the number of users in the model.
      */
+    @Override
     public int getNumUsers() {
         return getUsers().size();
     }
 
     /**
      * Method that clears all the maps contained in the model.
      */
+    @Override
     public void clear() {
         userItemPreferences.clear();
-        userItemTimestamps.clear();
-        itemUserPreferences.clear();
+        items.clear();
     }
 }

rival-core/src/main/java/net/recommenders/rival/core/DataModelIF.java

@@ -0,0 +1,81 @@
+/*
+ * Copyright 2015 recommenders.net.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package net.recommenders.rival.core;
+
+import java.util.Map;
+import java.util.Set;
+
+/**
+ * Interface for the data model used throughout the toolkit. Able to store
+ * users, items, and preferences.
+ *
+ * @author <a href="http://github.com/abellogin">Alejandro</a>, <a
+ * href="http://github.com/alansaid">Alan</a>
+ *
+ * @param <U> generic type for users
+ * @param <I> generic type for items
+ */
+public interface DataModelIF<U, I> {
+
+    /**
+     * Method that returns the preference map between users and items.
+     *
+     * @return the preference map between users and items.
+     */
+    public Map<U, Map<I, Double>> getUserItemPreferences();
+
+    /**
+     * Method that adds a preference to the model between a user and an item.
+     *
+     * @param u the user.
+     * @param i the item.
+     * @param d the preference.
+     */
+    public void addPreference(final U u, final I i, final Double d);
+
+    /**
+     * Method that returns the items in the model.
+     *
+     * @return the items in the model.
+     */
+    public Set<I> getItems();
+
+    /**
+     * Method that returns the users in the model.
+     *
+     * @return the users in the model.
+     */
+    public Set<U> getUsers();
+
+    /**
+     * Method that returns the number of items in the model.
+     *
+     * @return the number of items in the model.
+     */
+    public int getNumItems();
+
+    /**
+     * Method that returns the number of users in the model.
+     *
+     * @return the number of users in the model.
+     */
+    public int getNumUsers();
+
+    /**
+     * Method that clears all the maps contained in the model.
+     */
+    public void clear();
+}

rival-core/src/main/java/net/recommenders/rival/core/DataModelUtils.java

@@ -48,7 +48,7 @@ private DataModelUtils() {
      * @throws UnsupportedEncodingException when the requested encoding (UTF-8)
      * is not available.
      */
-    public static <U, I> void saveDataModel(final DataModel<U, I> dm, final String outfile, final boolean overwrite)
+    public static <U, I> void saveDataModel(final TemporalDataModelIF<U, I> dm, final String outfile, final boolean overwrite)
             throws FileNotFoundException, UnsupportedEncodingException {
         if (new File(outfile).exists() && !overwrite) {
             System.out.println("Ignoring " + outfile);

rival-core/src/main/java/net/recommenders/rival/core/Parser.java

@@ -29,11 +29,20 @@
 public interface Parser<U, I> {
 
     /**
-     * Parse data file.
+     * Parse a temporal data file.
      *
      * @param f The file to be parsed.
      * @return A dataset created from the file.
      * @throws IOException if the file cannot be read.
      */
-    DataModel<U, I> parseData(File f) throws IOException;
+    TemporalDataModelIF<U, I> parseTemporalData(File f) throws IOException;
+
+    /**
+     * Parse a data file.
+     *
+     * @param f The file to be parsed.
+     * @return A dataset created from the file.
+     * @throws IOException if the file cannot be read.
+     */
+    DataModelIF<U, I> parseData(File f) throws IOException;
 }

rival-core/src/main/java/net/recommenders/rival/core/ParserWithIdMapping.java

@@ -26,7 +26,18 @@
  * @param <U> generic type of users
  * @param <I> generic type of items
  */
-public interface ParserWithIdMapping<U, I> {
+public interface ParserWithIdMapping<U, I> extends Parser<U, I> {
+
+    /**
+     * Parse a temporal data file.
+     *
+     * @param f The file to be parsed.
+     * @param mapIdsPrefix The prefix of the file where the id mapping will be
+     * stored (and will be read from).
+     * @return A dataset created from the file.
+     * @throws IOException if the file cannot be read.
+     */
+    TemporalDataModelIF<U, I> parseTemporalData(File f, String mapIdsPrefix) throws IOException;
 
     /**
      * Parse data file.
@@ -37,5 +48,5 @@ public interface ParserWithIdMapping<U, I> {
      * @return The data model created from the file.
      * @throws IOException if the file cannot be read.
      */
-    DataModel<U, I> parseData(File f, String mapIdsPrefix) throws IOException;
+    DataModelIF<U, I> parseData(File f, String mapIdsPrefix) throws IOException;
 }