Example usage for org.apache.mahout.cf.taste.model DataModel getPreferencesForItem

Introduction

In this page you can find the example usage for org.apache.mahout.cf.taste.model DataModel getPreferencesForItem.

Prototype

PreferenceArray getPreferencesForItem(long itemID) throws TasteException;

Source Link

Usage

From source file:com.anjuke.romar.mahout.RecommenderWrapper.java

License:Apache License

@Override
public void removeItem(long itemID) throws TasteException {
    DataModel dataModel = _recommender.getDataModel();
    for (Preference p : dataModel.getPreferencesForItem(itemID)) {
        removePreference(p.getUserID(), itemID);
    }/*from   w w w . j a  v  a2s . co m*/
}

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From source file:lib.similarity.AbstractUnboundedSimilarity.java

License:Apache License

@Override
public final double itemSimilarity(long itemID1, long itemID2) throws TasteException {
    DataModel dataModel = getDataModel();
    PreferenceArray xPrefs = dataModel.getPreferencesForItem(itemID1);
    PreferenceArray yPrefs = dataModel.getPreferencesForItem(itemID2);
    int xLength = xPrefs.length();
    int yLength = yPrefs.length();

    if (xLength == 0 || yLength == 0) {
        return Double.NaN;
    }//from   w  ww .ja va  2  s .co m

    long xIndex = xPrefs.getUserID(0);
    long yIndex = yPrefs.getUserID(0);
    int xPrefIndex = 0;
    int yPrefIndex = 0;

    // No, pref inferrers and transforms don't appy here. I think.

    SimilarityAccumulator accum = getSimilarityAccumulator();

    while (true) {
        int compare = xIndex < yIndex ? -1 : xIndex > yIndex ? 1 : 0;
        if (compare == 0) {
            // Both users expressed a preference for the item
            double x = xPrefs.getValue(xPrefIndex);
            double y = yPrefs.getValue(yPrefIndex);

            accum.processPrefPair(x, y);
        }
        if (compare <= 0) {
            if (++xPrefIndex == xLength) {
                break;
            }
            xIndex = xPrefs.getUserID(xPrefIndex);
        }
        if (compare >= 0) {
            if (++yPrefIndex == yLength) {
                break;
            }
            yIndex = yPrefs.getUserID(yPrefIndex);
        }
    }

    double result;
    result = accum.computeResult();

    if (similarityTransform != null) {
        result = similarityTransform.transformSimilarity(itemID1, itemID2, result);
    }

    return result;
}

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From source file:org.easyrec.mahout.EasyrecInMemoryDataModelTest.java

License:Open Source License

@Test
public void testEasyrecDataModel_getPreferencesForItem() throws TasteException {
    DataModel easyrecDataModel = new EasyrecDataModel(TENANT_ID, RATE_ACTION_TYPE_ID, HAS_RATING_VALUES,
            mahoutDataModelMappingDAO);//from  www . j a  v a 2 s  . co m
    easyrecDataModel = new EasyrecInMemoryDataModel(easyrecDataModel);

    PreferenceArray preferences = easyrecDataModel.getPreferencesForItem(1);

    String ids = "";
    for (long id : preferences.getIDs()) {
        ids += id;
    }

    assertEquals("12", ids);

}

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From source file:org.easyrec.mahout.EasyrecInMemoryDataModelTest.java

License:Open Source License

@Test
public void testEasyrecDataModel_getBooleanPreferencesForItem() throws TasteException {
    DataModel easyrecDataModel = new EasyrecDataModel(TENANT_ID, BUY_ACTION_TYPE_ID, HAS_NO_RATING_VALUES,
            mahoutDataModelMappingDAO);//from  ww w  .j av  a 2  s.  c  o m
    easyrecDataModel = new EasyrecInMemoryDataModel(easyrecDataModel);

    PreferenceArray preferences = easyrecDataModel.getPreferencesForItem(10);

    String ids = "";
    for (long id : preferences.getIDs()) {
        ids += id;
    }

    assertEquals("12", ids);

}

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