weka.classifiers.evaluation

## Class TwoClassStats

- java.lang.Object
- - weka.classifiers.evaluation.TwoClassStats

- All Implemented Interfaces:
    RevisionHandler

      public class TwoClassStats
      extends java.lang.Object
      implements RevisionHandler

  Encapsulates performance functions for two-class problems.
  Version:
    $Revision: 10169 $
  Author:
    Len Trigg (len@reeltwo.com)

- - ### Constructor Summary

    Constructors
    Constructor and Description
    `TwoClassStats(double tp, double fp, double tn, double fn)` Creates the TwoClassStats with the given initial performance values.

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `ConfusionMatrix` | `getConfusionMatrix()` Generates a `ConfusionMatrix` representing the current two-class statistics, using class names "negative" and "positive".
    `double` | `getFallout()` Calculate the fallout.
    `double` | `getFalseNegative()` Gets the number of positive instances predicted as negative
    `double` | `getFalsePositive()` Gets the number of negative instances predicted as positive
    `double` | `getFalsePositiveRate()` Calculate the false positive rate.
    `double` | `getFMeasure()` Calculate the F-Measure.
    `double` | `getPrecision()` Calculate the precision.
    `double` | `getRecall()` Calculate the recall.
    `java.lang.String` | `getRevision()` Returns the revision string.
    `double` | `getTrueNegative()` Gets the number of negative instances predicted as negative
    `double` | `getTruePositive()` Gets the number of positive instances predicted as positive
    `double` | `getTruePositiveRate()` Calculate the true positive rate.
    `void` | `setFalseNegative(double fn)` Sets the number of positive instances predicted as negative
    `void` | `setFalsePositive(double fp)` Sets the number of negative instances predicted as positive
    `void` | `setTrueNegative(double tn)` Sets the number of negative instances predicted as negative
    `void` | `setTruePositive(double tp)` Sets the number of positive instances predicted as positive
    `java.lang.String` | `toString()` Returns a string containing the various performance measures for the current object

    - ### Methods inherited from class java.lang.Object

      `equals, getClass, hashCode, notify, notifyAll, wait, wait, wait`

- - ### Constructor Detail

    - #### TwoClassStats

          public TwoClassStats(double tp,
                       double fp,
                       double tn,
                       double fn)

      Creates the TwoClassStats with the given initial performance values.
      Parameters:
        `tp` - the number of correctly classified positives
        `fp` - the number of incorrectly classified negatives
        `tn` - the number of correctly classified negatives
        `fn` - the number of incorrectly classified positives

  - ### Method Detail

    - #### setTruePositive

          public void setTruePositive(double tp)

      Sets the number of positive instances predicted as positive

    - #### setFalsePositive

          public void setFalsePositive(double fp)

      Sets the number of negative instances predicted as positive

    - #### setTrueNegative

          public void setTrueNegative(double tn)

      Sets the number of negative instances predicted as negative

    - #### setFalseNegative

          public void setFalseNegative(double fn)

      Sets the number of positive instances predicted as negative

    - #### getTruePositive

          public double getTruePositive()

      Gets the number of positive instances predicted as positive

    - #### getFalsePositive

          public double getFalsePositive()

      Gets the number of negative instances predicted as positive

    - #### getTrueNegative

          public double getTrueNegative()

      Gets the number of negative instances predicted as negative

    - #### getFalseNegative

          public double getFalseNegative()

      Gets the number of positive instances predicted as negative

    - #### getTruePositiveRate

          public double getTruePositiveRate()

      Calculate the true positive rate. This is defined as

           correctly classified positives
           ------------------------------
                 total positives

      Returns:
        the true positive rate

    - #### getFalsePositiveRate

          public double getFalsePositiveRate()

      Calculate the false positive rate. This is defined as

           incorrectly classified negatives
           --------------------------------
                  total negatives

      Returns:
        the false positive rate

    - #### getPrecision

          public double getPrecision()

      Calculate the precision. This is defined as

           correctly classified positives
           ------------------------------
            total predicted as positive

      Returns:
        the precision

    - #### getRecall

          public double getRecall()

      Calculate the recall. This is defined as

           correctly classified positives
           ------------------------------
                 total positives

      (Which is also the same as the truePositiveRate.)

      Returns:
        the recall

    - #### getFMeasure

          public double getFMeasure()

      Calculate the F-Measure. This is defined as

           2 * recall * precision
           ----------------------
             recall + precision

      Returns:
        the F-Measure

    - #### getFallout

          public double getFallout()

      Calculate the fallout. This is defined as

           incorrectly classified negatives
           --------------------------------
             total predicted as positive

      Returns:
        the fallout

    - #### getConfusionMatrix

          public ConfusionMatrix getConfusionMatrix()

      Generates a `ConfusionMatrix` representing the current two-class statistics, using class names "negative" and "positive".
      Returns:
        a `ConfusionMatrix`.

    - #### toString

          public java.lang.String toString()

      Returns a string containing the various performance measures for the current object
      Overrides:
        `toString` in class `java.lang.Object`

    - #### getRevision

          public java.lang.String getRevision()

      Returns the revision string.
      Specified by:
        `getRevision` in interface `RevisionHandler`
      Returns:
        the revision