IntentModel.java

/* 
 * Copyright (C) 2015 Information Retrieval Group at Universidad Autónoma
 * de Madrid, http://ir.ii.uam.es
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 */
package es.uam.eps.ir.ranksys.diversity.intentaware;

import es.uam.eps.ir.ranksys.core.model.UserModel;
import java.util.Set;
import java.util.stream.Stream;

/**
 * Intent-aware model.
 *
 * @author Saúl Vargas (saul.vargas@uam.es)
 * @author Pablo Castells (pablo.castells@uam.es)
 * 
 * @param <U> type of the users
 * @param <I> type of the items
 * @param <F> type of the intent
 */
public abstract class IntentModel<U, I, F> extends UserModel<U> {

    /**
     * Constructor that caches user intent-aware models.
     *
     * @param targetUsers user whose intent-aware models are cached
     */
    public IntentModel(Stream<U> targetUsers) {
        super(targetUsers);
    }

    /**
     * Constructor that does not cache user intent-aware models.
     */
    public IntentModel() {
        super();
    }

    @Override
    protected abstract UserIntentModel<U, I, F> get(U user);

    @SuppressWarnings("unchecked")
    @Override
    public UserIntentModel<U, I, F> getModel(U user) {
        return (UserIntentModel<U, I, F>) super.getModel(user);
    }

    /**
     * User intent-aware model for {@link IntentModel}.
     * @param <U> user type
     * @param <I> item type
     * @param <F> feature type
     */
    public interface UserIntentModel<U, I, F> extends Model<U> {

        /**
         * Returns the intents considered in the intent model.
         *
         * @return the intents considered in the intent model
         */
        Set<F> getIntents();

        /**
         * Returns the intents associated with an item.
         *
         * @param i item
         * @return the intents associated with the item
         */
        Stream<F> getItemIntents(I i);

        /**
         * Returns the probability of an intent in the model.
         *
         * @param f intent
         * @return probability of an intent in the model
         */
        double pf_u(F f);
    }
}