title: Numerically Adding the contents of two dataframes (with different column names)
body: <p>A small part of my code is trying to create a computed column in a dataframe by numerically adding two dataframes (varying column names).
  However am facing an issue</p>
  
  <pre><code>elif any(df.filter(regex="INT : Q2")):
  df['ABC'] = ((df.filter(regex="INT : Q2", axis=1)/(PL_EURSGD[1])) + 
                                  (df.filter(regex="INT : Q1", axis=1)/(PL_EURSGD[0])))  
  
  ValueError: Wrong number of items passed 2, placement implies 1
  
  
  df.filter(regex="INT : Q2", axis=1)/(PL_EURSGD[1]) #becomes a dataframe in itself with column name as INT : Q2
  (df.filter(regex="INT : Q1", axis=1)/(PL_EURSGD[0]) #becomes another dataframe with column name as INT : Q1
  </code></pre>
  
  <p>Please note all the values are numeric, there is no missing value.
  Any suggestions why this is going wrong.</p>