class_docstr: Uses a Pandas DataFrame as the feed source, iterating directly over the
  tuples returned by "itertuples".
  
  This means that all parameters related to lines must have numeric
  values as indices into the tuples
  
  Note:
  
    - The ``dataname`` parameter is a Pandas DataFrame
  
    - A negative value in any of the parameters for the Data lines
      indicates it's not present in the DataFrame
      it is
class_docstr_tok: ["Uses","a","Pandas","DataFrame","as","the","feed","source",",","iterating","directly","over","the","tuples","returned","by","``","itertuples","''",".","This","means","that","all","parameters","related","to","lines","must","have","numeric","values","as","indices","into","the","tuples","Note",":","-","The","``","dataname","``","parameter","is","a","Pandas","DataFrame","-","A","negative","value","in","any","of","the","parameters","for","the","Data","lines","indicates","it","'s","not","present","in","the","DataFrame","it","is"]
code: def _load(self):
      try:
          row = next(self._rows)
      except StopIteration:
          return False
  
      # Set the standard datafields - except for datetime
      for datafield in self.getlinealiases():
          if datafield == "datetime":
              continue
  
          # get the column index
          colidx = getattr(self.params, datafield)
  
          if colidx < 0:
              # column not present -- skip
              continue
  
          # get the line to be set
          line = getattr(self.lines, datafield)
  
          # indexing for pandas: 1st is colum, then row
          line[0] = row[colidx]
  
      # datetime
      colidx = getattr(self.params, "datetime")
      tstamp = row[colidx]
  
      # convert to float via datetime and store it
      dt = tstamp.to_pydatetime()
      dtnum = date2num(dt)
  
      # get the line to be set
      line = getattr(self.lines, "datetime")
      line[0] = dtnum
  
      # Done ... return
      return True
  
file_path: backtrader/backtrader/feeds/pandafeed.py
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  from backtrader.utils.py3 import filter, string_types, integer_types
  from backtrader import date2num
  import backtrader.feed
label_desc: Use image node_id 2 for calling the PandasDirectData obj's underlying member method code with example usage: obj._load() and returns: True, False