title: pandas, apply with args which are dataframe row entries
body: <p>I have a pandas dataframe 'df' with two columns 'A' and 'B', I have a function with two arguments</p>
  
  <pre><code>def myfunction(B, A):
      # do something here to get the result
      return result
  </code></pre>
  
  <p>and I would like to apply it row-by-row to df using the 'apply' function</p>
  
  <pre><code>df['C'] = df['B'].apply(myfunction, args=(df['A'],))
  </code></pre>
  
  <p>but I get the error</p>
  
  <pre><code>ValueError: The truth value of a Series is ambiguous. Use a.empty, a.bool(), a.item(), a.any() or a.all().
  </code></pre>
  
  <p>whats happening here, it seems it takes df['A'] as the whole series! not just the row entry from that series as required.</p>