@Override
  public void beforeStart(UDFParameters parameters, UDTFConfigurations configurations)
      throws Exception {
    configurations.setAccessStrategy(new RowByRowAccessStrategy()).setOutputDataType(Type.INT32);
    // input param min is var start, param max is var end
    start = parameters.getDoubleOrDefault("min", -Double.MAX_VALUE);
    double end = parameters.getDoubleOrDefault("max", Double.MAX_VALUE);
    count = parameters.getIntOrDefault("count", 1);
    bucket = new int[count];
    gap = (end - start) / count;
  }
This function is used to calculate the distribution histogram of a single column of numerical
data.
library-udf/src/main/java/org/apache/iotdb/library/dprofile/UDTFHistogram.java