@Override
  public void transform(Row row, PointCollector collector) throws Exception {
    double v = Util.getValueAsDouble(row);
    if (Double.isFinite(v)) {
      valueList.add(v);
      timeList.add(row.getTime());
    }
  }
This function filters high frequency components.
library-udf/src/main/java/org/apache/iotdb/library/frequency/UDTFLowPass.java