@Override public Instances transformedHeader() throws Exception {
  if (m_eigenvalues == null) {
    throw new Exception("Principal components hasn't been built yet");
  }
  if (m_transBackToOriginal) {
    return m_originalSpaceFormat;
  }
 else {
    return m_transformedFormat;
  }
}

@ Override public Instances transformedHeader ( ) throws Exception { if ( m_eigenvalues == null ) { throw new Exception ( "Principal components hasn't been built yet" ) ; } if ( m_transBackToOriginal ) { return m_originalSpaceFormat ; } else { return m_transformedFormat ; } }
returns just the header for the transformed data ( ie . an empty set of instances . this is so that attributeselection can determine the structure of the transformed data without actually having to get all the transformed data through transformeddata ( ) .
