title: How to python pandas.DataFrame.fillna(method='pad') left to right?
body: <p>Title says it all, method=pad goes from top to bottom (vertical axis), but I would like to pad from left to right (horizontal axis). Should I just rotate the table? </p>
  
  <p>For example, I need the value in column A to update the NaN value in column B and so on. This works with rows, but not columns?</p>
  
  <p>I didn't find anything in the documentation:</p>
  
  <p><a href="http://pandas.pydata.org/pandas-docs/stable/missing_data.html" rel="nofollow">http://pandas.pydata.org/pandas-docs/stable/missing_data.html</a></p>
  
  <p><a href="http://pandas.pydata.org/pandas-docs/stable/generated/pandas.DataFrame.fillna.html" rel="nofollow">http://pandas.pydata.org/pandas-docs/stable/generated/pandas.DataFrame.fillna.html</a></p>