code: def populate_dataframe(index,columns, default_dict, dtype):
      
      new_df = pd.DataFrame(index=index,columns=columns)
      for fieldname,dt in zip(columns,dtype.descr):
          default = default_dict[fieldname]
          new_df.loc[:,fieldname] = default
          new_df.loc[:,fieldname] = new_df.loc[:,fieldname].astype(dt[1])
      return new_df
docs: helper function to populate a generic Pst dataframe attribute.  This
      function is called as part of constructing a generic Pst instance
  
      Parameters
      ----------
      index : (varies)
          something to use as the dataframe index
      columns: (varies)
          something to use as the dataframe columns
      default_dict : (dict)
          dictionary of default values for columns
      dtype : numpy.dtype
          dtype used to cast dataframe columns
  
      Returns
      -------
      new_df : pandas.DataFrame