title: pandas Timedelta error
body: <p>I'm getting errors when running the code samples from the pandas documentation.  </p>
  
  <p>I suspect it might be related to the version of pandas I'm using, but I haven't been able to confirm that.  </p>
  
  <pre><code>pandas VERSION 0.10.1  
  numpy VERSION 1.7.0  
  scipy VERSION 0.12.0.dev-14b1e07  
  </code></pre>
  
  <p>The below examples are taken directly from the pandas documentation here:  </p>
  
  <p><a href="http://pandas.pydata.org/pandas-docs/dev/timeseries.html#time-deltas" rel="nofollow">pandas - Time Deltas</a><br>
  This works  </p>
  
  <pre><code>from datetime import datetime, timedelta  
  from pandas import *  
  
  s  = Series(date_range('2012-1-1', periods=3, freq='D'))  
  s  
  
  Out[52]:  
  0   2012-01-01 00:00:00  
  1   2012-01-02 00:00:00  
  2   2012-01-03 00:00:00  
  </code></pre>
  
  <p>as does this  </p>
  
  <pre><code>td = Series([ timedelta(days=i) for i in range(3) ])  
  td  
  Out[53]:  
  0            0:00:00  
  1     1 day, 0:00:00  
  2    2 days, 0:00:00  
  
  df = DataFrame(dict(A = s, B = td))  
  df  
  Out[54]:  
                      A                B  
  0 2012-01-01 00:00:00          0:00:00  
  1 2012-01-02 00:00:00   1 day, 0:00:00  
  2 2012-01-03 00:00:00  2 days, 0:00:00  
  </code></pre>
  
  <p>This seems to be consistent with the expected output according to the documentation.  </p>
  
  <p>The next line in the sample code yields an error:  </p>
  
  <pre><code>df['C'] = df['A'] + df['B']  
  </code></pre>
  
  <p>...  </p>
  
  <pre><code>---------------------------------------------------------------------------
  TypeError                                 Traceback (most recent call last)
  &lt;ipython-input-55-7057e174d79e&gt; in &lt;module&gt;()
  ----&gt; 1 df['C'] = df['A'] + df['B']
  
  /Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pandas/core/series.pyc in wrapper(self, other)
       91             if self.index.equals(other.index):
       92                 name = _maybe_match_name(self, other)
  ---&gt; 93                 return Series(wrap_results(na_op(lvalues, rvalues)),
       94                               index=self.index, name=name)
       95 
  
  /Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pandas/core/series.pyc in na_op(x, y)
       63             if isinstance(y, np.ndarray):
       64                 mask = notnull(x) &amp; notnull(y)
  ---&gt; 65                 result[mask] = op(x[mask], y[mask])
       66             else:
       67                 mask = notnull(x)
  
  TypeError: ufunc add cannot use operands with types dtype('&lt;M8[ns]') and dtype('O')
  </code></pre>
  
  <p>Datatypes:  </p>
  
  <pre><code>df.dtypes
  
  Out[56]: 
  A    datetime64[ns]
  B            object
  </code></pre>
  
  <p>Similarly, I get an error when I do addition/subtraction:</p>
  
  <pre><code>s - s.max()
  
  &lt;ipython-input-57-8d53e24db927&gt; in &lt;module&gt;()
  ----&gt; 1 s - s.max()
  
  /Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pandas/core/series.pyc in wrapper(self, other)
       78 
       79         if (com.is_datetime64_dtype(self) and
  ---&gt; 80             com.is_datetime64_dtype(other)):
       81             lvalues = lvalues.view('i8')
       82             rvalues = rvalues.view('i8')
  
  /Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pandas/core/common.pyc in is_datetime64_dtype(arr_or_dtype)
     1003         tipo = arr_or_dtype.type
     1004     else:
  -&gt; 1005         tipo = arr_or_dtype.dtype.type
     1006     return issubclass(tipo, np.datetime64)
     1007 
  
  AttributeError: 'Timestamp' object has no attribute 'dtype'
  </code></pre>
  
  <p>This code is in a gist for easy reference. </p>
  
  <p><a href="https://gist.github.com/hernamesbarbara/5061972" rel="nofollow">https://gist.github.com/hernamesbarbara/5061972</a></p>
  
  <p>Thanks for any help or suggestions; it is much appreciated.</p>
  
  <p>-Austin</p>