How to use

numPendingOutput

method

in

weka.filters.unsupervised.attribute.Center

/**
 * Signify that this batch of input to the filter is finished. 
 * If the filter requires all instances prior to filtering,
 * output() may now be called to retrieve the filtered instances.
 *
 * @return true             if there are instances pending output
 * @throws IllegalStateException     if no input structure has been defined
 */
public boolean batchFinished() {
 if (getInputFormat() == null)
  throw new IllegalStateException("No input instance format defined");
 if (m_Means == null) {
  Instances input = getInputFormat();
  m_Means = new double[input.numAttributes()];
  for (int i = 0; i < input.numAttributes(); i++) {
   if (input.attribute(i).isNumeric() &&
       (input.classIndex() != i)) {
    m_Means[i] = input.meanOrMode(i);
   }
  }
  // Convert pending input instances
  for (int i = 0; i < input.numInstances(); i++)
   convertInstance(input.instance(i));
 }
 // Free memory
 flushInput();
 m_NewBatch = true;
 return (numPendingOutput() != 0);
}

/**
 * Signify that this batch of input to the filter is finished. 
 * If the filter requires all instances prior to filtering,
 * output() may now be called to retrieve the filtered instances.
 *
 * @return true             if there are instances pending output
 * @throws IllegalStateException     if no input structure has been defined
 */
public boolean batchFinished() {
 if (getInputFormat() == null)
  throw new IllegalStateException("No input instance format defined");
 if (m_Means == null) {
  Instances input = getInputFormat();
  m_Means = new double[input.numAttributes()];
  for (int i = 0; i < input.numAttributes(); i++) {
   if (input.attribute(i).isNumeric() &&
       (input.classIndex() != i)) {
    m_Means[i] = input.meanOrMode(i);
   }
  }
  // Convert pending input instances
  for (int i = 0; i < input.numInstances(); i++)
   convertInstance(input.instance(i));
 }
 // Free memory
 flushInput();
 m_NewBatch = true;
 return (numPendingOutput() != 0);
}