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## weka.classifiers
Class Evaluation

    java.lang.Object
      weka.classifiers.Evaluation

All Implemented Interfaces:
  Summarizable

    public class Evaluation

extends java.lang.Object
implements Summarizable

Class for evaluating machine learning models.

-------------------------------------------------------------------

General options when evaluating a learning scheme from the command-line:

-t filename
Name of the file with the training data. (required)

-T filename
Name of the file with the test data. If missing a cross-validation is performed.

-c index
Index of the class attribute (1, 2, ...; default: last).

-x number
The number of folds for the cross-validation (default: 10).

-s seed
Random number seed for the cross-validation (default: 1).

-m filename
The name of a file containing a cost matrix.

-l filename
Loads classifier from the given file.

-d filename
Saves classifier built from the training data into the given file.

-v
Outputs no statistics for the training data.

-o
Outputs statistics only, not the classifier.

-i
Outputs information-retrieval statistics per class.

-k
Outputs information-theoretic statistics.

-p range
Outputs predictions for test instances, along with the attributes in the specified range (and nothing else). Use '-p 0' if no attributes are desired.

-r
Outputs cumulative margin distribution (and nothing else).

-g
Only for classifiers that implement "Graphable." Outputs the graph representation of the classifier (and nothing else).

-------------------------------------------------------------------

Example usage as the main of a classifier (called FunkyClassifier): `

     public static void main(String [] args) {
       try {
         Classifier scheme = new FunkyClassifier();
         System.out.println(Evaluation.evaluateModel(scheme, args));
       } catch (Exception e) {
         System.err.println(e.getMessage());
       }
     }

`

------------------------------------------------------------------

Example usage from within an application: `

     Instances trainInstances = ... instances got from somewhere
     Instances testInstances = ... instances got from somewhere
     Classifier scheme = ... scheme got from somewhere

     Evaluation evaluation = new Evaluation(trainInstances);
     evaluation.evaluateModel(scheme, testInstances);
     System.out.println(evaluation.toSummaryString());

`

Version:
  $Revision: 1.53.2.6 $
Author:
  Eibe Frank (eibe@cs.waikato.ac.nz), Len Trigg (trigg@cs.waikato.ac.nz)

Constructor Summary
`Evaluation(Instances data)` Initializes all the counters for the evaluation.
`Evaluation(Instances data, CostMatrix costMatrix)` Initializes all the counters for the evaluation and also takes a cost matrix as parameter.

Method Summary
`double` | `avgCost()` Gets the average cost, that is, total cost of misclassifications (incorrect plus unclassified) over the total number of instances.
`double[][]` | `confusionMatrix()` Returns a copy of the confusion matrix.
`double` | `correct()` Gets the number of instances correctly classified (that is, for which a correct prediction was made).
`double` | `correlationCoefficient()` Returns the correlation coefficient if the class is numeric.
`void` | `crossValidateModel(Classifier classifier, Instances data, int numFolds, java.util.Random random)` Performs a (stratified if class is nominal) cross-validation for a classifier on a set of instances.
`void` | `crossValidateModel(java.lang.String classifierString, Instances data, int numFolds, java.lang.String[] options, java.util.Random random)` Performs a (stratified if class is nominal) cross-validation for a classifier on a set of instances.
`boolean` | `equals(java.lang.Object obj)` Tests whether the current evaluation object is equal to another evaluation object
`double` | `errorRate()` Returns the estimated error rate or the root mean squared error (if the class is numeric).
`double[]` | `evaluateModel(Classifier classifier, Instances data)` Evaluates the classifier on a given set of instances.
`static java.lang.String` | `evaluateModel(Classifier classifier, java.lang.String[] options)` Evaluates a classifier with the options given in an array of strings.
`static java.lang.String` | `evaluateModel(java.lang.String classifierString, java.lang.String[] options)` Evaluates a classifier with the options given in an array of strings.
`double` | `evaluateModelOnce(Classifier classifier, Instance instance)` Evaluates the classifier on a single instance.
`double` | `evaluateModelOnce(double[] dist, Instance instance)` Evaluates the supplied distribution on a single instance.
`void` | `evaluateModelOnce(double prediction, Instance instance)` Evaluates the supplied prediction on a single instance.
`double` | `falseNegativeRate(int classIndex)` Calculate the false negative rate with respect to a particular class.
`double` | `falsePositiveRate(int classIndex)` Calculate the false positive rate with respect to a particular class.
`double` | `fMeasure(int classIndex)` Calculate the F-Measure with respect to a particular class.
`double` | `incorrect()` Gets the number of instances incorrectly classified (that is, for which an incorrect prediction was made).
`double` | `kappa()` Returns value of kappa statistic if class is nominal.
`double` | `KBInformation()` Return the total Kononenko & Bratko Information score in bits
`double` | `KBMeanInformation()` Return the Kononenko & Bratko Information score in bits per instance.
`double` | `KBRelativeInformation()` Return the Kononenko & Bratko Relative Information score
`static void` | `main(java.lang.String[] args)` A test method for this class.
`double` | `meanAbsoluteError()` Returns the mean absolute error.
`double` | `meanPriorAbsoluteError()` Returns the mean absolute error of the prior.
`double` | `numFalseNegatives(int classIndex)` Calculate number of false negatives with respect to a particular class.
`double` | `numFalsePositives(int classIndex)` Calculate number of false positives with respect to a particular class.
`double` | `numInstances()` Gets the number of test instances that had a known class value (actually the sum of the weights of test instances with known class value).
`double` | `numTrueNegatives(int classIndex)` Calculate the number of true negatives with respect to a particular class.
`double` | `numTruePositives(int classIndex)` Calculate the number of true positives with respect to a particular class.
`double` | `pctCorrect()` Gets the percentage of instances correctly classified (that is, for which a correct prediction was made).
`double` | `pctIncorrect()` Gets the percentage of instances incorrectly classified (that is, for which an incorrect prediction was made).
`double` | `pctUnclassified()` Gets the percentage of instances not classified (that is, for which no prediction was made by the classifier).
`double` | `precision(int classIndex)` Calculate the precision with respect to a particular class.
`double` | `priorEntropy()` Calculate the entropy of the prior distribution
`double` | `recall(int classIndex)` Calculate the recall with respect to a particular class.
`double` | `relativeAbsoluteError()` Returns the relative absolute error.
`double` | `rootMeanPriorSquaredError()` Returns the root mean prior squared error.
`double` | `rootMeanSquaredError()` Returns the root mean squared error.
`double` | `rootRelativeSquaredError()` Returns the root relative squared error if the class is numeric.
`void` | `setPriors(Instances train)` Sets the class prior probabilities
`double` | `SFEntropyGain()` Returns the total SF, which is the null model entropy minus the scheme entropy.
`double` | `SFMeanEntropyGain()` Returns the SF per instance, which is the null model entropy minus the scheme entropy, per instance.
`double` | `SFMeanPriorEntropy()` Returns the entropy per instance for the null model
`double` | `SFMeanSchemeEntropy()` Returns the entropy per instance for the scheme
`double` | `SFPriorEntropy()` Returns the total entropy for the null model
`double` | `SFSchemeEntropy()` Returns the total entropy for the scheme
`java.lang.String` | `toClassDetailsString()` Generates a breakdown of the accuracy for each class (with default title), incorporating various information-retrieval statistics, such as true/false positive rate, precision/recall/F-Measure.
`java.lang.String` | `toClassDetailsString(java.lang.String title)` Generates a breakdown of the accuracy for each class, incorporating various information-retrieval statistics, such as true/false positive rate, precision/recall/F-Measure.
`java.lang.String` | `toCumulativeMarginDistributionString()` Output the cumulative margin distribution as a string suitable for input for gnuplot or similar package.
`java.lang.String` | `toMatrixString()` Calls toMatrixString() with a default title.
`java.lang.String` | `toMatrixString(java.lang.String title)` Outputs the performance statistics as a classification confusion matrix.
`java.lang.String` | `toSummaryString()` Calls toSummaryString() with no title and no complexity stats
`java.lang.String` | `toSummaryString(boolean printComplexityStatistics)` Calls toSummaryString() with a default title.
`java.lang.String` | `toSummaryString(java.lang.String title, boolean printComplexityStatistics)` Outputs the performance statistics in summary form.
`double` | `totalCost()` Gets the total cost, that is, the cost of each prediction times the weight of the instance, summed over all instances.
`double` | `trueNegativeRate(int classIndex)` Calculate the true negative rate with respect to a particular class.
`double` | `truePositiveRate(int classIndex)` Calculate the true positive rate with respect to a particular class.
`double` | `unclassified()` Gets the number of instances not classified (that is, for which no prediction was made by the classifier).
`void` | `updatePriors(Instance instance)` Updates the class prior probabilities (when incrementally training)
`void` | `useNoPriors()` disables the use of priors, e.g., in case of de-serialized schemes that have no access to the original training set, but are evaluated on a set set.

Methods inherited from class java.lang.Object
`getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail

### Evaluation

    public Evaluation(Instances data)
               throws java.lang.Exception

  Initializes all the counters for the evaluation. Use `useNoPriors()` if the dataset is the test set and you can't initialize with the priors from the training set via `setPriors(Instances)`.

  Parameters:
    `data` - set of training instances, to get some header information and prior class distribution information
  Throws:
    `java.lang.Exception` - if the class is not defined
  See Also:
    `useNoPriors()`, `setPriors(Instances)`

### Evaluation

    public Evaluation(Instances data,
                      CostMatrix costMatrix)
               throws java.lang.Exception

  Initializes all the counters for the evaluation and also takes a cost matrix as parameter. Use `useNoPriors()` if the dataset is the test set and you can't initialize with the priors from the training set via `setPriors(Instances)`.

  Parameters:
    `data` - set of training instances, to get some header information and prior class distribution information
    `costMatrix` - the cost matrix---if null, default costs will be used
  Throws:
    `java.lang.Exception` - if cost matrix is not compatible with data, the class is not defined or the class is numeric
  See Also:
    `useNoPriors()`, `setPriors(Instances)`

Method Detail

### confusionMatrix

    public double[][] confusionMatrix()

  Returns a copy of the confusion matrix.

  Returns:
    a copy of the confusion matrix as a two-dimensional array

### crossValidateModel

    public void crossValidateModel(Classifier classifier,
                                   Instances data,
                                   int numFolds,
                                   java.util.Random random)
                            throws java.lang.Exception

  Performs a (stratified if class is nominal) cross-validation for a classifier on a set of instances. Now performs a deep copy of the classifier before each call to buildClassifier() (just in case the classifier is not initialized properly).

  Parameters:
    `classifier` - the classifier with any options set.
    `data` - the data on which the cross-validation is to be performed
    `numFolds` - the number of folds for the cross-validation
    `random` - random number generator for randomization
  Throws:
    `java.lang.Exception` - if a classifier could not be generated successfully or the class is not defined

### crossValidateModel

    public void crossValidateModel(java.lang.String classifierString,
                                   Instances data,
                                   int numFolds,
                                   java.lang.String[] options,
                                   java.util.Random random)
                            throws java.lang.Exception

  Performs a (stratified if class is nominal) cross-validation for a classifier on a set of instances.

  Parameters:
    `classifierString` - a string naming the class of the classifier
    `data` - the data on which the cross-validation is to be performed
    `numFolds` - the number of folds for the cross-validation
    `options` - the options to the classifier. Any options
    `random` - the random number generator for randomizing the data accepted by the classifier will be removed from this array.
  Throws:
    `java.lang.Exception` - if a classifier could not be generated successfully or the class is not defined

### evaluateModel

    public static java.lang.String evaluateModel(java.lang.String classifierString,
                                                 java.lang.String[] options)
                                          throws java.lang.Exception

  Evaluates a classifier with the options given in an array of strings.

  Valid options are:

  -t filename
  Name of the file with the training data. (required)

  -T filename
  Name of the file with the test data. If missing a cross-validation is performed.

  -c index
  Index of the class attribute (1, 2, ...; default: last).

  -x number
  The number of folds for the cross-validation (default: 10).

  -s seed
  Random number seed for the cross-validation (default: 1).

  -m filename
  The name of a file containing a cost matrix.

  -l filename
  Loads classifier from the given file.

  -d filename
  Saves classifier built from the training data into the given file.

  -v
  Outputs no statistics for the training data.

  -o
  Outputs statistics only, not the classifier.

  -i
  Outputs detailed information-retrieval statistics per class.

  -k
  Outputs information-theoretic statistics.

  -p range
  Outputs predictions for test instances, along with the attributes in the specified range (and nothing else). Use '-p 0' if no attributes are desired.

  -r
  Outputs cumulative margin distribution (and nothing else).

  -g
  Only for classifiers that implement "Graphable." Outputs the graph representation of the classifier (and nothing else).

  Parameters:
    `classifierString` - class of machine learning classifier as a string
    `options` - the array of string containing the options
  Returns:
    a string describing the results
  Throws:
    `java.lang.Exception` - if model could not be evaluated successfully

### main

    public static void main(java.lang.String[] args)

  A test method for this class. Just extracts the first command line argument as a classifier class name and calls evaluateModel.

  Parameters:
    `args` - an array of command line arguments, the first of which must be the class name of a classifier.

### evaluateModel

    public static java.lang.String evaluateModel(Classifier classifier,
                                                 java.lang.String[] options)
                                          throws java.lang.Exception

  Evaluates a classifier with the options given in an array of strings.

  Valid options are:

  -t name of training file
  Name of the file with the training data. (required)

  -T name of test file
  Name of the file with the test data. If missing a cross-validation is performed.

  -c class index
  Index of the class attribute (1, 2, ...; default: last).

  -x number of folds
  The number of folds for the cross-validation (default: 10).

  -s random number seed
  Random number seed for the cross-validation (default: 1).

  -m file with cost matrix
  The name of a file containing a cost matrix.

  -l name of model input file
  Loads classifier from the given file.

  -d name of model output file
  Saves classifier built from the training data into the given file.

  -v
  Outputs no statistics for the training data.

  -o
  Outputs statistics only, not the classifier.

  -i
  Outputs detailed information-retrieval statistics per class.

  -k
  Outputs information-theoretic statistics.

  -p
  Outputs predictions for test instances (and nothing else).

  -r
  Outputs cumulative margin distribution (and nothing else).

  -g
  Only for classifiers that implement "Graphable." Outputs the graph representation of the classifier (and nothing else).

  Parameters:
    `classifier` - machine learning classifier
    `options` - the array of string containing the options
  Returns:
    a string describing the results
  Throws:
    `java.lang.Exception` - if model could not be evaluated successfully

### evaluateModel

    public double[] evaluateModel(Classifier classifier,
                                  Instances data)
                           throws java.lang.Exception

  Evaluates the classifier on a given set of instances. Note that the data must have exactly the same format (e.g. order of attributes) as the data used to train the classifier! Otherwise the results will generally be meaningless.

  Parameters:
    `classifier` - machine learning classifier
    `data` - set of test instances for evaluation
  Returns:
    the predictions
  Throws:
    `java.lang.Exception` - if model could not be evaluated successfully

### evaluateModelOnce

    public double evaluateModelOnce(Classifier classifier,
                                    Instance instance)
                             throws java.lang.Exception

  Evaluates the classifier on a single instance.

  Parameters:
    `classifier` - machine learning classifier
    `instance` - the test instance to be classified
  Returns:
    the prediction made by the clasifier
  Throws:
    `java.lang.Exception` - if model could not be evaluated successfully or the data contains string attributes

### evaluateModelOnce

    public double evaluateModelOnce(double[] dist,
                                    Instance instance)
                             throws java.lang.Exception

  Evaluates the supplied distribution on a single instance.

  Parameters:
    `dist` - the supplied distribution
    `instance` - the test instance to be classified
  Returns:
    the prediction
  Throws:
    `java.lang.Exception` - if model could not be evaluated successfully

### evaluateModelOnce

    public void evaluateModelOnce(double prediction,
                                  Instance instance)
                           throws java.lang.Exception

  Evaluates the supplied prediction on a single instance.

  Parameters:
    `prediction` - the supplied prediction
    `instance` - the test instance to be classified
  Throws:
    `java.lang.Exception` - if model could not be evaluated successfully

### numInstances

    public final double numInstances()

  Gets the number of test instances that had a known class value (actually the sum of the weights of test instances with known class value).

  Returns:
    the number of test instances with known class

### incorrect

    public final double incorrect()

  Gets the number of instances incorrectly classified (that is, for which an incorrect prediction was made). (Actually the sum of the weights of these instances)

  Returns:
    the number of incorrectly classified instances

### pctIncorrect

    public final double pctIncorrect()

  Gets the percentage of instances incorrectly classified (that is, for which an incorrect prediction was made).

  Returns:
    the percent of incorrectly classified instances (between 0 and 100)

### totalCost

    public final double totalCost()

  Gets the total cost, that is, the cost of each prediction times the weight of the instance, summed over all instances.

  Returns:
    the total cost

### avgCost

    public final double avgCost()

  Gets the average cost, that is, total cost of misclassifications (incorrect plus unclassified) over the total number of instances.

  Returns:
    the average cost.

### correct

    public final double correct()

  Gets the number of instances correctly classified (that is, for which a correct prediction was made). (Actually the sum of the weights of these instances)

  Returns:
    the number of correctly classified instances

### pctCorrect

    public final double pctCorrect()

  Gets the percentage of instances correctly classified (that is, for which a correct prediction was made).

  Returns:
    the percent of correctly classified instances (between 0 and 100)

### unclassified

    public final double unclassified()

  Gets the number of instances not classified (that is, for which no prediction was made by the classifier). (Actually the sum of the weights of these instances)

  Returns:
    the number of unclassified instances

### pctUnclassified

    public final double pctUnclassified()

  Gets the percentage of instances not classified (that is, for which no prediction was made by the classifier).

  Returns:
    the percent of unclassified instances (between 0 and 100)

### errorRate

    public final double errorRate()

  Returns the estimated error rate or the root mean squared error (if the class is numeric). If a cost matrix was given this error rate gives the average cost.

  Returns:
    the estimated error rate (between 0 and 1, or between 0 and maximum cost)

### kappa

    public final double kappa()

  Returns value of kappa statistic if class is nominal.

  Returns:
    the value of the kappa statistic

### correlationCoefficient

    public final double correlationCoefficient()
                                        throws java.lang.Exception

  Returns the correlation coefficient if the class is numeric.

  Returns:
    the correlation coefficient
  Throws:
    `java.lang.Exception` - if class is not numeric

### meanAbsoluteError

    public final double meanAbsoluteError()

  Returns the mean absolute error. Refers to the error of the predicted values for numeric classes, and the error of the predicted probability distribution for nominal classes.

  Returns:
    the mean absolute error

### meanPriorAbsoluteError

    public final double meanPriorAbsoluteError()

  Returns the mean absolute error of the prior.

  Returns:
    the mean absolute error

### relativeAbsoluteError

    public final double relativeAbsoluteError()
                                       throws java.lang.Exception

  Returns the relative absolute error.

  Returns:
    the relative absolute error
  Throws:
    `java.lang.Exception` - if it can't be computed

### rootMeanSquaredError

    public final double rootMeanSquaredError()

  Returns the root mean squared error.

  Returns:
    the root mean squared error

### rootMeanPriorSquaredError

    public final double rootMeanPriorSquaredError()

  Returns the root mean prior squared error.

  Returns:
    the root mean prior squared error

### rootRelativeSquaredError

    public final double rootRelativeSquaredError()

  Returns the root relative squared error if the class is numeric.

  Returns:
    the root relative squared error

### priorEntropy

    public final double priorEntropy()
                              throws java.lang.Exception

  Calculate the entropy of the prior distribution

  Returns:
    the entropy of the prior distribution
  Throws:
    `java.lang.Exception` - if the class is not nominal

### KBInformation

    public final double KBInformation()
                               throws java.lang.Exception

  Return the total Kononenko & Bratko Information score in bits

  Returns:
    the K&B information score
  Throws:
    `java.lang.Exception` - if the class is not nominal

### KBMeanInformation

    public final double KBMeanInformation()
                                   throws java.lang.Exception

  Return the Kononenko & Bratko Information score in bits per instance.

  Returns:
    the K&B information score
  Throws:
    `java.lang.Exception` - if the class is not nominal

### KBRelativeInformation

    public final double KBRelativeInformation()
                                       throws java.lang.Exception

  Return the Kononenko & Bratko Relative Information score

  Returns:
    the K&B relative information score
  Throws:
    `java.lang.Exception` - if the class is not nominal

### SFPriorEntropy

    public final double SFPriorEntropy()

  Returns the total entropy for the null model

  Returns:
    the total null model entropy

### SFMeanPriorEntropy

    public final double SFMeanPriorEntropy()

  Returns the entropy per instance for the null model

  Returns:
    the null model entropy per instance

### SFSchemeEntropy

    public final double SFSchemeEntropy()

  Returns the total entropy for the scheme

  Returns:
    the total scheme entropy

### SFMeanSchemeEntropy

    public final double SFMeanSchemeEntropy()

  Returns the entropy per instance for the scheme

  Returns:
    the scheme entropy per instance

### SFEntropyGain

    public final double SFEntropyGain()

  Returns the total SF, which is the null model entropy minus the scheme entropy.

  Returns:
    the total SF

### SFMeanEntropyGain

    public final double SFMeanEntropyGain()

  Returns the SF per instance, which is the null model entropy minus the scheme entropy, per instance.

  Returns:
    the SF per instance

### toCumulativeMarginDistributionString

    public java.lang.String toCumulativeMarginDistributionString()
                                                          throws java.lang.Exception

  Output the cumulative margin distribution as a string suitable for input for gnuplot or similar package.

  Returns:
    the cumulative margin distribution
  Throws:
    `java.lang.Exception` - if the class attribute is nominal

### toSummaryString

    public java.lang.String toSummaryString()

  Calls toSummaryString() with no title and no complexity stats

  Specified by:
    `toSummaryString` in interface `Summarizable`
  Returns:
    a summary description of the classifier evaluation

### toSummaryString

    public java.lang.String toSummaryString(boolean printComplexityStatistics)

  Calls toSummaryString() with a default title.

  Parameters:
    `printComplexityStatistics` - if true, complexity statistics are returned as well
  Returns:
    the summary string

### toSummaryString

    public java.lang.String toSummaryString(java.lang.String title,
                                            boolean printComplexityStatistics)

  Outputs the performance statistics in summary form. Lists number (and percentage) of instances classified correctly, incorrectly and unclassified. Outputs the total number of instances classified, and the number of instances (if any) that had no class value provided.

  Parameters:
    `title` - the title for the statistics
    `printComplexityStatistics` - if true, complexity statistics are returned as well
  Returns:
    the summary as a String

### toMatrixString

    public java.lang.String toMatrixString()
                                    throws java.lang.Exception

  Calls toMatrixString() with a default title.

  Returns:
    the confusion matrix as a string
  Throws:
    `java.lang.Exception` - if the class is numeric

### toMatrixString

    public java.lang.String toMatrixString(java.lang.String title)
                                    throws java.lang.Exception

  Outputs the performance statistics as a classification confusion matrix. For each class value, shows the distribution of predicted class values.

  Parameters:
    `title` - the title for the confusion matrix
  Returns:
    the confusion matrix as a String
  Throws:
    `java.lang.Exception` - if the class is numeric

### toClassDetailsString

    public java.lang.String toClassDetailsString()
                                          throws java.lang.Exception

  Generates a breakdown of the accuracy for each class (with default title), incorporating various information-retrieval statistics, such as true/false positive rate, precision/recall/F-Measure. Should be useful for ROC curves, recall/precision curves.

  Returns:
    the statistics presented as a string
  Throws:
    `java.lang.Exception` - if class is not nominal

### toClassDetailsString

    public java.lang.String toClassDetailsString(java.lang.String title)
                                          throws java.lang.Exception

  Generates a breakdown of the accuracy for each class, incorporating various information-retrieval statistics, such as true/false positive rate, precision/recall/F-Measure. Should be useful for ROC curves, recall/precision curves.

  Parameters:
    `title` - the title to prepend the stats string with
  Returns:
    the statistics presented as a string
  Throws:
    `java.lang.Exception` - if class is not nominal

### numTruePositives

    public double numTruePositives(int classIndex)

  Calculate the number of true positives with respect to a particular class. This is defined as

       correctly classified positives

  Parameters:
    `classIndex` - the index of the class to consider as "positive"
  Returns:
    the true positive rate

### truePositiveRate

    public double truePositiveRate(int classIndex)

  Calculate the true positive rate with respect to a particular class. This is defined as

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

  Parameters:
    `classIndex` - the index of the class to consider as "positive"
  Returns:
    the true positive rate

### numTrueNegatives

    public double numTrueNegatives(int classIndex)

  Calculate the number of true negatives with respect to a particular class. This is defined as

       correctly classified negatives

  Parameters:
    `classIndex` - the index of the class to consider as "positive"
  Returns:
    the true positive rate

### trueNegativeRate

    public double trueNegativeRate(int classIndex)

  Calculate the true negative rate with respect to a particular class. This is defined as

       correctly classified negatives
       ------------------------------
             total negatives

  Parameters:
    `classIndex` - the index of the class to consider as "positive"
  Returns:
    the true positive rate

### numFalsePositives

    public double numFalsePositives(int classIndex)

  Calculate number of false positives with respect to a particular class. This is defined as

       incorrectly classified negatives

  Parameters:
    `classIndex` - the index of the class to consider as "positive"
  Returns:
    the false positive rate

### falsePositiveRate

    public double falsePositiveRate(int classIndex)

  Calculate the false positive rate with respect to a particular class. This is defined as

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

  Parameters:
    `classIndex` - the index of the class to consider as "positive"
  Returns:
    the false positive rate

### numFalseNegatives

    public double numFalseNegatives(int classIndex)

  Calculate number of false negatives with respect to a particular class. This is defined as

       incorrectly classified positives

  Parameters:
    `classIndex` - the index of the class to consider as "positive"
  Returns:
    the false positive rate

### falseNegativeRate

    public double falseNegativeRate(int classIndex)

  Calculate the false negative rate with respect to a particular class. This is defined as

       incorrectly classified positives
       --------------------------------
              total positives

  Parameters:
    `classIndex` - the index of the class to consider as "positive"
  Returns:
    the false positive rate

### recall

    public double recall(int classIndex)

  Calculate the recall with respect to a particular class. This is defined as

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

  (Which is also the same as the truePositiveRate.)

  Parameters:
    `classIndex` - the index of the class to consider as "positive"
  Returns:
    the recall

### precision

    public double precision(int classIndex)

  Calculate the precision with respect to a particular class. This is defined as

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

  Parameters:
    `classIndex` - the index of the class to consider as "positive"
  Returns:
    the precision

### fMeasure

    public double fMeasure(int classIndex)

  Calculate the F-Measure with respect to a particular class. This is defined as

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

  Parameters:
    `classIndex` - the index of the class to consider as "positive"
  Returns:
    the F-Measure

### setPriors

    public void setPriors(Instances train)
                   throws java.lang.Exception

  Sets the class prior probabilities

  Parameters:
    `train` - the training instances used to determine the prior probabilities
  Throws:
    `java.lang.Exception` - if the class attribute of the instances is not set

### updatePriors

    public void updatePriors(Instance instance)
                      throws java.lang.Exception

  Updates the class prior probabilities (when incrementally training)

  Parameters:
    `instance` - the new training instance seen
  Throws:
    `java.lang.Exception` - if the class of the instance is not set

### useNoPriors

    public void useNoPriors()

  disables the use of priors, e.g., in case of de-serialized schemes that have no access to the original training set, but are evaluated on a set set.

### equals

    public boolean equals(java.lang.Object obj)

  Tests whether the current evaluation object is equal to another evaluation object

  Overrides:
    `equals` in class `java.lang.Object`
  Parameters:
    `obj` - the object to compare against
  Returns:
    true if the two objects are equal

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