title: KeyError When I want try to plot
body: <p>I get an error whenever I try to perform actions on U objects. I always get a KeyError. I have tried many times to plot U (last statement.)</p>
  
  <pre><code>import pandas as pd
  users =pd.read_csv('./users.csv',sep=',',parse_dates=[30])
  users.head()
  users.columns.get_loc("WhenCreated")
  users['Month'] = users['WhenCreated'].dt.month
  users.head()
  UsersCreatedin2017=users['WhenCreated'] &gt; '2017-01-01'
  users2017=users[UsersCreatedin2017].copy()
  users2017[['Month','UserPrincipalName']].groupby('Month').count()
  u=users2017[['Month','UserPrincipalName']].groupby('Month').count().copy()
  u.plot(kind='line', x='Month', y='UserPrincipalName')
  </code></pre>
  
  <p>where I go the following error</p>
  
  <pre><code>KeyError                                  Traceback (most recent call last)
  C:\ProgramData\Anaconda3\lib\site-packages\pandas\core\indexes\base.py in get_loc(self, key, method, tolerance)
     2392             try:
  -&gt; 2393                 return self._engine.get_loc(key)
     2394             except KeyError:
  
  pandas\_libs\index.pyx in pandas._libs.index.IndexEngine.get_loc (pandas\_libs\index.c:5239)()
  
  pandas\_libs\index.pyx in pandas._libs.index.IndexEngine.get_loc (pandas\_libs\index.c:5085)()
  
  pandas\_libs\hashtable_class_helper.pxi in pandas._libs.hashtable.PyObjectHashTable.get_item (pandas\_libs\hashtable.c:20405)()
  
  pandas\_libs\hashtable_class_helper.pxi in pandas._libs.hashtable.PyObjectHashTable.get_item (pandas\_libs\hashtable.c:20359)()
  
  KeyError: 'Month'
  
  During handling of the above exception, another exception occurred:
  
  KeyError                                  Traceback (most recent call last)
  &lt;ipython-input-7-841cfe522e84&gt; in &lt;module&gt;()
       13 #u.sort_values(by='Month', ascending=True)
       14 #u.plot.line('Month','UserPrincipalName')
  ---&gt; 15 u.plot(kind='line', x='Month', y='UserPrincipalName')
       16 
       17 
  
  C:\ProgramData\Anaconda3\lib\site-packages\pandas\plotting\_core.py in __call__(self, x, y, kind, ax, subplots, sharex, sharey, layout, figsize, use_index, title, grid, legend, style, logx, logy, loglog, xticks, yticks, xlim, ylim, rot, fontsize, colormap, table, yerr, xerr, secondary_y, sort_columns, **kwds)
     2618                           fontsize=fontsize, colormap=colormap, table=table,
     2619                           yerr=yerr, xerr=xerr, secondary_y=secondary_y,
  -&gt; 2620                           sort_columns=sort_columns, **kwds)
     2621     __call__.__doc__ = plot_frame.__doc__
     2622 
  
  C:\ProgramData\Anaconda3\lib\site-packages\pandas\plotting\_core.py in plot_frame(data, x, y, kind, ax, subplots, sharex, sharey, layout, figsize, use_index, title, grid, legend, style, logx, logy, loglog, xticks, yticks, xlim, ylim, rot, fontsize, colormap, table, yerr, xerr, secondary_y, sort_columns, **kwds)
     1855                  yerr=yerr, xerr=xerr,
     1856                  secondary_y=secondary_y, sort_columns=sort_columns,
  -&gt; 1857                  **kwds)
     1858 
     1859 
  
  C:\ProgramData\Anaconda3\lib\site-packages\pandas\plotting\_core.py in _plot(data, x, y, subplots, ax, kind, **kwds)
     1660                 if is_integer(x) and not data.columns.holds_integer():
     1661                     x = data.columns[x]
  -&gt; 1662                 data = data.set_index(x)
     1663 
     1664             if y is not None:
  
  C:\ProgramData\Anaconda3\lib\site-packages\pandas\core\frame.py in set_index(self, keys, drop, append, inplace, verify_integrity)
     2926                 names.append(None)
     2927             else:
  -&gt; 2928                 level = frame[col]._values
     2929                 names.append(col)
     2930                 if drop:
  
  C:\ProgramData\Anaconda3\lib\site-packages\pandas\core\frame.py in __getitem__(self, key)
     2060             return self._getitem_multilevel(key)
     2061         else:
  -&gt; 2062             return self._getitem_column(key)
     2063 
     2064     def _getitem_column(self, key):
  
  C:\ProgramData\Anaconda3\lib\site-packages\pandas\core\frame.py in _getitem_column(self, key)
     2067         # get column
     2068         if self.columns.is_unique:
  -&gt; 2069             return self._get_item_cache(key)
     2070 
     2071         # duplicate columns &amp; possible reduce dimensionality
  
  C:\ProgramData\Anaconda3\lib\site-packages\pandas\core\generic.py in _get_item_cache(self, item)
     1532         res = cache.get(item)
     1533         if res is None:
  -&gt; 1534             values = self._data.get(item)
     1535             res = self._box_item_values(item, values)
     1536             cache[item] = res
  
  C:\ProgramData\Anaconda3\lib\site-packages\pandas\core\internals.py in get(self, item, fastpath)
     3588 
     3589             if not isnull(item):
  -&gt; 3590                 loc = self.items.get_loc(item)
     3591             else:
     3592                 indexer = np.arange(len(self.items))[isnull(self.items)]
  
  C:\ProgramData\Anaconda3\lib\site-packages\pandas\core\indexes\base.py in get_loc(self, key, method, tolerance)
     2393                 return self._engine.get_loc(key)
     2394             except KeyError:
  -&gt; 2395                 return self._engine.get_loc(self._maybe_cast_indexer(key))
     2396 
     2397         indexer = self.get_indexer([key], method=method, tolerance=tolerance)
  
  pandas\_libs\index.pyx in pandas._libs.index.IndexEngine.get_loc (pandas\_libs\index.c:5239)()
  
  pandas\_libs\index.pyx in pandas._libs.index.IndexEngine.get_loc (pandas\_libs\index.c:5085)()
  
  pandas\_libs\hashtable_class_helper.pxi in pandas._libs.hashtable.PyObjectHashTable.get_item (pandas\_libs\hashtable.c:20405)()
  
  pandas\_libs\hashtable_class_helper.pxi in pandas._libs.hashtable.PyObjectHashTable.get_item (pandas\_libs\hashtable.c:20359)()
  
  KeyError: 'Month'
  </code></pre>
  
  <p>I try to u.plot() but i got the following output
  </p>
  
  <p>where data I am trying to plot is :
      UserPrincipalName
  Month<br>
  1   61
  2   53
  3   44
  4   31
  5   34
  6   21
  7   28
  8   196
  9   42</p>