<h4 dir="auto">Code Sample, a copy-pastable example if possible</h4>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="import pandas as pd
data = [{'id': 1, 'buyer': 'A'}, {'id': 2, 'buyer': 'B'}]
df = pd.DataFrame(data, index=pd.date_range('2016-01-01', periods=2))
resampler = df.groupby('id').resample('1D')"><pre class="notranslate"><code class="notranslate">import pandas as pd
data = [{'id': 1, 'buyer': 'A'}, {'id': 2, 'buyer': 'B'}]
df = pd.DataFrame(data, index=pd.date_range('2016-01-01', periods=2))
resampler = df.groupby('id').resample('1D')
</code></pre></div>
<p dir="auto">If I then run <code class="notranslate">resampler['buyer'].count()</code> first time, it will output normally:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="id
1   2016-01-01    1
2   2016-01-02    1
Name: buyer, dtype: int64"><pre class="notranslate"><code class="notranslate">id
1   2016-01-01    1
2   2016-01-02    1
Name: buyer, dtype: int64
</code></pre></div>
<p dir="auto">If I then run <code class="notranslate">resampler['buyer'].count()</code> again, it will report error:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="/usr/local/bin/ipython:1: FutureWarning: .resample() is now a deferred operation
use .resample(...).mean() instead of .resample(...)
  #!/usr/local/opt/python/bin/python2.7
---------------------------------------------------------------------------
KeyError                                  Traceback (most recent call last)
&lt;ipython-input-30-5714547cf98c&gt; in &lt;module&gt;()
----&gt; 1 resampler['buyer'].count()

/usr/local/lib/python2.7/site-packages/pandas/tseries/resample.pyc in __getitem__(self, key)
    179             # compat for deprecated
    180             if isinstance(self.obj, com.ABCSeries):
--&gt; 181                 return self._deprecated()[key]
    182
    183             raise

/usr/local/lib/python2.7/site-packages/pandas/core/frame.pyc in __getitem__(self, key)
   1995             return self._getitem_multilevel(key)
   1996         else:
-&gt; 1997             return self._getitem_column(key)
   1998
   1999     def _getitem_column(self, key):

/usr/local/lib/python2.7/site-packages/pandas/core/frame.pyc in _getitem_column(self, key)
   2002         # get column
   2003         if self.columns.is_unique:
-&gt; 2004             return self._get_item_cache(key)
   2005
   2006         # duplicate columns &amp; possible reduce dimensionality

/usr/local/lib/python2.7/site-packages/pandas/core/generic.pyc in _get_item_cache(self, item)
   1348         res = cache.get(item)
   1349         if res is None:
-&gt; 1350             values = self._data.get(item)
   1351             res = self._box_item_values(item, values)
   1352             cache[item] = res

/usr/local/lib/python2.7/site-packages/pandas/core/internals.pyc in get(self, item, fastpath)
   3288
   3289             if not isnull(item):
-&gt; 3290                 loc = self.items.get_loc(item)
   3291             else:
   3292                 indexer = np.arange(len(self.items))[isnull(self.items)]

/usr/local/lib/python2.7/site-packages/pandas/indexes/base.pyc in get_loc(self, key, method, tolerance)
   1945                 return self._engine.get_loc(key)
   1946             except KeyError:
-&gt; 1947                 return self._engine.get_loc(self._maybe_cast_indexer(key))
   1948
   1949         indexer = self.get_indexer([key], method=method, tolerance=tolerance)

pandas/index.pyx in pandas.index.IndexEngine.get_loc (pandas/index.c:4154)()

pandas/index.pyx in pandas.index.IndexEngine.get_loc (pandas/index.c:4018)()

pandas/hashtable.pyx in pandas.hashtable.PyObjectHashTable.get_item (pandas/hashtable.c:12368)()

pandas/hashtable.pyx in pandas.hashtable.PyObjectHashTable.get_item (pandas/hashtable.c:12322)()

KeyError: 'buyer'"><pre class="notranslate"><code class="notranslate">/usr/local/bin/ipython:1: FutureWarning: .resample() is now a deferred operation
use .resample(...).mean() instead of .resample(...)
  #!/usr/local/opt/python/bin/python2.7
---------------------------------------------------------------------------
KeyError                                  Traceback (most recent call last)
&lt;ipython-input-30-5714547cf98c&gt; in &lt;module&gt;()
----&gt; 1 resampler['buyer'].count()

/usr/local/lib/python2.7/site-packages/pandas/tseries/resample.pyc in __getitem__(self, key)
    179             # compat for deprecated
    180             if isinstance(self.obj, com.ABCSeries):
--&gt; 181                 return self._deprecated()[key]
    182
    183             raise

/usr/local/lib/python2.7/site-packages/pandas/core/frame.pyc in __getitem__(self, key)
   1995             return self._getitem_multilevel(key)
   1996         else:
-&gt; 1997             return self._getitem_column(key)
   1998
   1999     def _getitem_column(self, key):

/usr/local/lib/python2.7/site-packages/pandas/core/frame.pyc in _getitem_column(self, key)
   2002         # get column
   2003         if self.columns.is_unique:
-&gt; 2004             return self._get_item_cache(key)
   2005
   2006         # duplicate columns &amp; possible reduce dimensionality

/usr/local/lib/python2.7/site-packages/pandas/core/generic.pyc in _get_item_cache(self, item)
   1348         res = cache.get(item)
   1349         if res is None:
-&gt; 1350             values = self._data.get(item)
   1351             res = self._box_item_values(item, values)
   1352             cache[item] = res

/usr/local/lib/python2.7/site-packages/pandas/core/internals.pyc in get(self, item, fastpath)
   3288
   3289             if not isnull(item):
-&gt; 3290                 loc = self.items.get_loc(item)
   3291             else:
   3292                 indexer = np.arange(len(self.items))[isnull(self.items)]

/usr/local/lib/python2.7/site-packages/pandas/indexes/base.pyc in get_loc(self, key, method, tolerance)
   1945                 return self._engine.get_loc(key)
   1946             except KeyError:
-&gt; 1947                 return self._engine.get_loc(self._maybe_cast_indexer(key))
   1948
   1949         indexer = self.get_indexer([key], method=method, tolerance=tolerance)

pandas/index.pyx in pandas.index.IndexEngine.get_loc (pandas/index.c:4154)()

pandas/index.pyx in pandas.index.IndexEngine.get_loc (pandas/index.c:4018)()

pandas/hashtable.pyx in pandas.hashtable.PyObjectHashTable.get_item (pandas/hashtable.c:12368)()

pandas/hashtable.pyx in pandas.hashtable.PyObjectHashTable.get_item (pandas/hashtable.c:12322)()

KeyError: 'buyer'
</code></pre></div>
<p dir="auto">If I run <code class="notranslate">df.groupby('id').resample('1D')['buyer'].count()</code> instead of <code class="notranslate">resampler['buyer'].count()</code>, the problem will not appear.</p>
<p dir="auto">What's the problem?</p>
<h4 dir="auto">output of <code class="notranslate">pd.show_versions()</code></h4>
<h2 dir="auto">INSTALLED VERSIONS</h2>
<p dir="auto">commit: None<br>
python: 2.7.11.final.0<br>
python-bits: 64<br>
OS: Darwin<br>
OS-release: 15.4.0<br>
machine: x86_64<br>
processor: i386<br>
byteorder: little<br>
LC_ALL: None<br>
LANG: zh_CN.UTF-8</p>
<p dir="auto">pandas: 0.18.1<br>
nose: None<br>
pip: 8.1.1<br>
setuptools: 19.4<br>
Cython: None<br>
numpy: 1.11.0<br>
scipy: None<br>
statsmodels: None<br>
xarray: None<br>
IPython: 4.2.0<br>
sphinx: 1.3.5<br>
patsy: None<br>
dateutil: 2.5.3<br>
pytz: 2016.4<br>
blosc: None<br>
bottleneck: None<br>
tables: None<br>
numexpr: None<br>
matplotlib: None<br>
openpyxl: None<br>
xlrd: None<br>
xlwt: None<br>
xlsxwriter: None<br>
lxml: None<br>
bs4: 4.4.1<br>
html5lib: None<br>
httplib2: None<br>
apiclient: None<br>
sqlalchemy: 1.0.12<br>
pymysql: None<br>
psycopg2: None<br>
jinja2: 2.8<br>
boto: None<br>
pandas_datareader: None</p>
<p dir="auto">Followup to <a class="issue-link js-issue-link" data-error-text="Failed to load title" data-id="324182009" data-permission-text="Title is private" data-url="https://github.com/pandas-dev/pandas/issues/21109" data-hovercard-type="pull_request" data-hovercard-url="/pandas-dev/pandas/pull/21109/hovercard" href="https://github.com/pandas-dev/pandas/pull/21109">#21109</a></p>
<p dir="auto">We'll need to refactor <code class="notranslate">scripts/announce.py</code> to update the list of contributors on each build.</p>
<p dir="auto">Then we can enable spellcheck in the Travis doc build.</p>