Example usage for weka.core Instances numInstances

List of usage examples for weka.core Instances numInstances

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Introduction

In this page you can find the example usage for weka.core Instances numInstances.

Prototype


publicint numInstances()

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Document

Returns the number of instances in the dataset.

Usage

From source file:edu.umbc.cs.maple.utils.WekaUtils.java

License:Open Source License

/** Uses the given model to predict the classes of the data.
 * @param model//  ww w.j av  a  2  s  .co m
 * @param data
 * @return An array of the class predictions.
 */
public static int[] predictClasses(Classifier model, Instances data) {
    int[] predictions = new int[data.numInstances()];
    int numInstances = data.numInstances();
    for (int instIdx = 0; instIdx < numInstances; instIdx++) {
        try {
            predictions[instIdx] = (int) model.classifyInstance(data.instance(instIdx));
        } catch (Exception e) {
            predictions[instIdx] = -1;
        }
    }
    return predictions;
}

From source file:edu.umbc.cs.maple.utils.WekaUtils.java

License:Open Source License

/** Gets the class labels for a set of instances.
 * @param data/*from  ww  w  .  j a va  2s. co m*/
 * @return a vector of the class labels for the data set, with one entry per instance
 */
public static int[] getLabels(Instances data) {
    int[] classLabels = new int[data.numInstances()];
    for (int instIdx = 0; instIdx < classLabels.length; instIdx++) {
        classLabels[instIdx] = (int) data.instance(instIdx).classValue();
    }
    return classLabels;
}

From source file:edu.umbc.cs.maple.utils.WekaUtils.java

License:Open Source License

/** Gets the class values for a set of instances.
 * @param data//  www . j a  v a2  s  .  c  o m
 * @return a vector of the class values for the data set, with one entry per instance
 */
public static double[] getClassValues(Instances data) {
    double[] classLabels = new double[data.numInstances()];
    for (int instIdx = 0; instIdx < classLabels.length; instIdx++) {
        classLabels[instIdx] = data.instance(instIdx).classValue();
    }
    return classLabels;
}

From source file:edu.umbc.cs.maple.utils.WekaUtils.java

License:Open Source License

/** Converts the instances in the given dataset to binary, setting the specified labels to positive.
 * Note this method is destructive to data, directly modifying its contents.
 * @param data the multiclass dataset to be converted to binary.
 * @param positiveClassValue the class value to treat as positive.
 *///from   w  w w  .ja  v a2 s .c  o m
public static void convertMulticlassToBinary(Instances data, String positiveClassValue) {

    // ensure that data is nominal
    if (!data.classAttribute().isNominal())
        throw new IllegalArgumentException("Instances must have a nominal class.");

    // create the new class attribute
    FastVector newClasses = new FastVector(2);
    newClasses.addElement("Y");
    newClasses.addElement("N");
    Attribute newClassAttribute = new Attribute("class", newClasses);

    // alter the class attribute to be binary
    int newClassAttIdx = data.classIndex();
    data.insertAttributeAt(newClassAttribute, newClassAttIdx);
    int classAttIdx = data.classIndex();

    // set the instances classes to be binary, with the labels [Y,N] (indices 0 and 1 respectively)
    int numInstances = data.numInstances();
    for (int instIdx = 0; instIdx < numInstances; instIdx++) {
        Instance inst = data.instance(instIdx);
        if (inst.stringValue(classAttIdx).equals(positiveClassValue)) {
            inst.setValue(newClassAttIdx, 0); // set it to the first class, which will be Y
        } else {
            inst.setValue(newClassAttIdx, 1); // set it to the second class, which will be 0
        }
    }

    // switch the class index to the new class and delete the old class
    data.setClassIndex(newClassAttIdx);
    data.deleteAttributeAt(classAttIdx);

    // alter the dataset name
    data.setRelationName(data.relationName() + "-" + positiveClassValue);
}

From source file:edu.umbc.cs.maple.utils.WekaUtils.java

License:Open Source License

/** Determines whether a data set has equal class priors.
 * @param data//w  ww .  j  a  v  a2 s .  c o  m
 * @return whether the data set has equal class priors
 */
public static boolean equalClassPriors(Instances data) {
    double[] counts = new double[data.numClasses()];
    int numInstances = data.numInstances();
    for (int i = 0; i < numInstances; i++) {
        Instance inst = data.instance(i);
        int classValueIdx = (int) Math.round(inst.classValue());
        counts[classValueIdx] = counts[classValueIdx] + 1;
    }

    // compute the mean
    double meanCount = MathUtils.sum(counts) / counts.length;
    double[] meanArray = new double[counts.length];
    for (int i = 0; i < meanArray.length; i++) {
        meanArray[i] = meanCount;
    }

    // compute the rmse
    double rmse = MathUtils.rmse(meanArray, counts);

    // compute 2.5% of the possible 
    double deviationAllowed = Math.ceil(0.025 * meanCount);

    if (rmse <= deviationAllowed)
        return true;
    else
        return false;
}

From source file:edu.umbc.cs.maple.utils.WekaUtils.java

License:Open Source License

/** Gets the weights of each instance in a dataset as an array.
 * @param data the dataset of instances/*w  ww . j  a  v a  2 s .  c  om*/
 * @return the weights of the instances as an array.
 */
public static double[] getWeights(Instances data) {
    int numInstances = data.numInstances();
    double[] weights = new double[numInstances];
    for (int instIdx = 0; instIdx < numInstances; instIdx++) {
        weights[instIdx] = data.instance(instIdx).weight();
    }
    return weights;
}

From source file:edu.umbc.cs.maple.utils.WekaUtils.java

License:Open Source License

/** Converts a set of instances to svm-light format
 * @param data the weka instances//from w  ww.  ja  v  a 2  s.c o m
 * @return the weka instances in svm-light format
 */
public static String arffToSVMLight(Instances data, SVMLightLabelFormat labelFormat) {

    if (labelFormat == SVMLightLabelFormat.CLASSIFICATION && data.numClasses() != 2) {
        throw new IllegalArgumentException(
                "SVM-light classification label format requires that the data contain only two classes.");
    }

    String str = "";
    String endline = System.getProperty("line.separator");

    int numInstances = data.numInstances();
    int numAttributes = data.numAttributes();
    int classAttIdx = data.classIndex();

    for (int instIdx = 0; instIdx < numInstances; instIdx++) {

        Instance inst = data.instance(instIdx);

        // convert the instance label
        if (labelFormat == SVMLightLabelFormat.CLASSIFICATION) {
            str += (inst.classValue() == 0) ? "-1" : "1";
        } else {
            str += inst.classValue();
        }

        str += " ";

        // convert each feature
        for (int attIdx = 0; attIdx < numAttributes; attIdx++) {
            // skip the class attribute
            if (attIdx == classAttIdx)
                continue;
            str += (attIdx + 1) + ":" + inst.value(attIdx) + " ";
        }

        // append the instance info string
        str += "# " + instIdx;

        str += endline;
    }

    return str;
}

From source file:edu.utexas.cs.tactex.utils.RegressionUtils.java

License:Open Source License

/**
 * adding y attributes with values//  w w w  .  j av  a 2  s  .c o  m
 */
public static Instances addYforWeka(Instances xInsts, Double[] y) {

    Instances xyInsts = addYforWeka(xInsts);

    if (y.length != xInsts.numInstances()) {
        log.error("cannot add y to instances since y.length != numInstances");
    }

    // initialize all y values
    int n = xInsts.numAttributes() - 1;
    for (int i = 0; i < y.length; ++i) {
        xInsts.get(i).setValue(n, y[i]);
    }

    return xyInsts;
}

From source file:edu.utexas.cs.tactex.utils.RegressionUtils.java

License:Open Source License

public static Double leaveOneOutErrorLinRegLambda(double lambda, Instances data) {

    // MANUAL //  ww w.  ja va2s . c o m

    // create a linear regression classifier with Xy_polynorm data
    LinearRegression linreg = createLinearRegression();
    linreg.setRidge(lambda);

    double mse = 0;
    for (int i = 0; i < data.numInstances(); ++i) {
        log.info("fold " + i);
        Instances train = data.trainCV(data.numInstances(), i);
        log.info("train");
        Instances test = data.testCV(data.numInstances(), i);
        log.info("test");
        double actualY = data.instance(i).classValue();
        log.info("actualY");
        try {
            linreg.buildClassifier(train);
            log.info("buildClassifier");
        } catch (Exception e) {
            log.error("failed to build classifier in cross validation", e);
            return null;

        }
        double predictedY = 0;
        try {
            predictedY = linreg.classifyInstance(test.instance(0));
            log.info("predictedY");
        } catch (Exception e) {
            log.error("failed to classify in cross validation", e);
            return null;
        }
        double error = predictedY - actualY;
        log.info("error " + error);
        mse += error * error;
        log.info("mse " + mse);
    }
    if (data.numInstances() == 0) {
        log.error("no instances in leave-one-out data");
        return null;
    }
    mse /= data.numInstances();
    log.info("mse " + mse);
    return mse;

    //     // USING WEKA 
    // 
    //     // create evaluation object
    //     Evaluation eval = null;
    //     try {
    //       eval = new Evaluation(data);
    //     } catch (Exception e) {
    //       log.error("weka Evaluation() creation threw exception", e);      
    //       //e.printStackTrace();    
    //       return null;
    //     }
    //     
    //     // create a linear regression classifier with Xy_polynorm data
    //     LinearRegression linreg = createLinearRegression();
    //     linreg.setRidge(lambda);
    // //    try {
    // //      linreg.buildClassifier(data);
    // //    } catch (Exception e) {
    // //      log.error("FAILED: linear regression threw exception", e);
    // //      //e.printStackTrace();    
    // //      return null;
    // //    }
    //     
    //     // initialize the evaluation object
    //     Classifier classifier = linreg;
    //     int numFolds = data.numInstances();
    //     Random random = new Random(0);
    //     try {
    //       eval.crossValidateModel(classifier , data , numFolds , random);
    //     } catch (Exception e) {
    //       log.error("crossvalidation threw exception", e);
    //       //e.printStackTrace();    
    //       return null;
    //     }
    //     
    //     double mse = eval.errorRate();
    //     return mse;
}

From source file:edu.washington.cs.knowitall.summarization.RedundancyClassifier.java

License:Open Source License

/**
 * //from w ww  . ja  v a2  s . c  o m
 * @param fstSentence
 * @param sndSentence
 * @return if the sentence are redundant
 * @throws Exception
 */
public boolean redundant(Sentence fstSentence, Sentence sndSentence) {
    if (redundantMap.containsKey(fstSentence.getKey() + "::" + sndSentence.getKey())) {
        return redundantMap.get(fstSentence.getKey() + "::" + sndSentence.getKey());
    }
    // Set up the instances.
    String header = getHeader();
    String features = getFeatures(fstSentence, sndSentence, false, -1);
    StringReader testReader = new StringReader(header + features + ",0.0" + "\n");
    Instances unlabeled = setupInstances(testReader);

    try {
        // label instances
        if (unlabeled.numInstances() > 0) {
            double clsLabel = tree.classifyInstance(unlabeled.instance(0));
            if (clsLabel == 0.0) {
                redundantMap.put(fstSentence.getKey() + "::" + sndSentence.getKey(), true);
                redundantMap.put(sndSentence.getKey() + "::" + fstSentence.getKey(), true);
                return true;
            } else {
                redundantMap.put(fstSentence.getKey() + "::" + sndSentence.getKey(), false);
                redundantMap.put(sndSentence.getKey() + "::" + fstSentence.getKey(), false);
                return false;
            }
        }
    } catch (FileNotFoundException e) {
        System.err.println("File not found error");
        e.printStackTrace();
    } catch (Exception e) {
        e.printStackTrace();
    }
    return false;
}