Example usage for weka.classifiers.evaluation ThresholdCurve getThresholdInstance

Introduction

In this page you can find the example usage for weka.classifiers.evaluation ThresholdCurve getThresholdInstance.

Prototype

public static int getThresholdInstance(Instances tcurve, double threshold) 

Source Link

Document

Gets the index of the instance with the closest threshold value to the desired target

Usage

From source file:meka.core.Metrics.java

License:Open Source License

/** Get Data for Plotting PR and ROC curves. */
public static Instances curveDataMacroAveraged(int Y[][], double P[][]) {

    // Note: 'Threshold' contains the probability threshold that gives rise to the previous performance values.

    Instances curveData[] = curveData(Y, P);

    int L = curveData.length;

    int noNullIndex = -1;

    for (int i = 0; i < curveData.length; i++) {
        if (curveData[i] == null) {
            L--;/*w ww.  j a  v  a2 s .  c  om*/
        } else {
            if (noNullIndex == -1) {
                // checking for the first curveData that is not null (=does not consist of
                // only missing values or 0s)
                noNullIndex = i;
            }

        }

    }

    Instances avgCurve = new Instances(curveData[noNullIndex], 0);
    int D = avgCurve.numAttributes();

    for (double t = 0.0; t < 1.; t += 0.01) {
        Instance x = (Instance) curveData[noNullIndex].instance(0).copy();
        //System.out.println("x1\n"+x);
        boolean firstloop = true;
        for (int j = 0; j < L; j++) {

            // if there are only missing values in a column, curveData[j] is null

            if (curveData[j] == null) {
                continue;
            }

            int i = ThresholdCurve.getThresholdInstance(curveData[j], t);
            if (firstloop) {
                // reset
                for (int a = 0; a < D; a++) {
                    x.setValue(a, curveData[j].instance(i).value(a) * 1. / L);
                }
                firstloop = false;
            } else {
                // add
                for (int a = 0; a < D; a++) {
                    double v = x.value(a);
                    x.setValue(a, v + curveData[j].instance(i).value(a) * 1. / L);
                }
            }
        }
        //System.out.println("x2\n"+x);
        avgCurve.add(x);
    }

    /*
      System.out.println(avgCurve);
      System.exit(1);
            
      // Average everything
      for (int i = 0; i < avgCurve.numInstances(); i++) {
      for(int j = 0; j < L; j++) {
      for (int a = 0; a < D; a++) {
      double o = avgCurve.instance(i).value(a);
      avgCurve.instance(i).setValue(a, o / L);
      }
      }
      }
    */
    return avgCurve;
}

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