code: public double falseAlarmRate() {
          if(binaryPositiveClass != null && numClasses() == 2){
              return (falsePositiveRate(binaryPositiveClass) + falseNegativeRate(binaryPositiveClass)) / 2.0;
          }
          return (falsePositiveRate() + falseNegativeRate()) / 2.0;
      }
docs: False Alarm Rate (FAR) reflects rate of misclassified to classified records
  <a href="http://ro.ecu.edu.au/cgi/viewcontent.cgi?article=1058&context=isw">http://ro.ecu.edu.au/cgi/viewcontent.cgi?article=1058&context=isw</a><br>
  Note: value returned will differ depending on number of classes and settings.<br>
  1. For binary classification, if the positive class is set (via default value of 1, via constructor,
  or via {@link #setBinaryPositiveClass(Integer)}), the returned value will be for the specified positive class
  only.<br>
  2. For the multi-class case, or when {@link #getBinaryPositiveClass()} is null, the returned value is macro-averaged
  across all classes. i.e., is macro-averaged false alarm rate)
  
  @return the fpr for the outcomes