title: Python/Pandas - ValueError: Incompatible indexer with Series
body: <p>I have a dataframe:</p>
  
  <pre><code>df:
  
          A      B 
  id
   3   'Yes'    23
   5   'Yes'    67
   6    'No'    56
   8    'No'    23
  </code></pre>
  
  <p>I have another dataframe:</p>
  
  <pre><code>calc:
         A    B
  id   
   3   'No'   4 
  </code></pre>
  
  <p>I would like to update df with calc values. I'm trying to use the following:</p>
  
  <pre><code>tgsm.loc[i]=calc
  </code></pre>
  
  <p>However, that doesn't work. I keep getting the following error:</p>
  
  <pre><code>File "/Library/Frameworks/Python.framework/Versions/3.5/lib/python3.5/site-packages/pandas/core/indexing.py", line 693, in _align_series
  raise ValueError('Incompatible indexer with Series')
  ValueError: Incompatible indexer with Series
  </code></pre>
  
  <p>If  try <code>tgsm.loc[i]=calc[i]</code>, it gets me to this other error:</p>
  
  <pre><code>File "pandas/index.pyx", line 137, in pandas.index.IndexEngine.get_loc (pandas/index.c:4154)
  File "pandas/index.pyx", line 159, in pandas.index.IndexEngine.get_loc (pandas/index.c:4018)
  File "pandas/hashtable.pyx", line 675, in pandas.hashtable.PyObjectHashTable.get_item (pandas/hashtable.c:12368)
  File "pandas/hashtable.pyx", line 683, in pandas.hashtable.PyObjectHashTable.get_item (pandas/hashtable.c:12322)
  KeyError: 3
  </code></pre>
  
  <p>Can anyone help enlightening my journey?</p>