private void transformInt(Row row) throws IOException {
    int v = row.getInt(0);
    intMin = Math.min(intMin, v);
    intMax = Math.max(intMax, v);
  }
This function is used to calculate the spread of time series, that is, the maximum value minus
the minimum value.
library-udf/src/main/java/org/apache/iotdb/library/dprofile/UDAFSpread.java