code: def transform_img_num(x):
      # deal with abnormal data of img_num
      if x == "上海":
          return 0.0
      elif isinstance(x, float):
          return float(x)
      else:  # for string inputs
          return float(eval(x))
  
file_path: BigDL/python/friesian/example/multi_task/data_processing.py
imports: import os
  from argparse import ArgumentParser
  from bigdl.dllib.utils.log4Error import invalidInputError
  from bigdl.orca import init_orca_context, stop_orca_context
  from bigdl.friesian.feature import FeatureTable
label_desc: Use image node_id 1 for calling a global function with example usage: transform_img_num(x) and returns: int, float, float