Example usage for org.apache.mahout.cf.taste.model PreferenceArray getUserID

Introduction

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

Prototype

long getUserID(int i);

Source Link

Usage

From source file:com.anjuke.romar.mahout.persistence.FilePreferenceSource.java

License:Apache License

@Override
public void compact() {
    // ????//from  ww  w.j a v a  2 s  .co m
    final long version = getCurrentVersion() - 1;
    if (version < 0) {
        return;
    }
    File latestSnapshotFile = getLatestSnapshotFile();
    if (latestSnapshotFile != null && getSnapshotFileVersion(latestSnapshotFile) == version) {
        return;
    }

    synchronized (_snapshotWriterLock) {
        PrintWriter snapshotWriter = createWriter(getSnapshotFile(version));
        try {
            final List<File> logFileList = getLogFileListUntilVersion(version);
            List<File> fileToIt = new ArrayList<File>(logFileList);
            if (latestSnapshotFile != null) {
                fileToIt.add(0, latestSnapshotFile);
            }
            PreferenceIterator it = new LogFileIterator(fileToIt);
            FastByIDMap<PreferenceArray> data = new FastByIDMap<PreferenceArray>();
            while (it.hasNext()) {
                Preference pref = it.next();
                if (it.getType() == PreferenceType.ADD) {
                    Util.applyAdd(data, pref);
                } else if (it.getType() == PreferenceType.DELETE) {
                    Util.applyRemove(data, pref);
                }
            }

            for (Entry<Long, PreferenceArray> entry : data.entrySet()) {
                PreferenceArray array = entry.getValue();
                for (int i = 0, length = array.length(); i < length; i++) {
                    long userID = array.getUserID(i);
                    long itemID = array.getItemID(i);
                    float value = array.getValue(i);
                    snapshotWriter.print(userID);
                    snapshotWriter.print(',');
                    snapshotWriter.print(itemID);
                    snapshotWriter.print(',');
                    snapshotWriter.println(value);
                }
            }

            snapshotWriter.flush();
            snapshotWriter.close();
            removeFile();
        } finally {
            snapshotWriter.close();
        }
    }
}

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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;
    }//www.  j a v a  2 s .c  o  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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