我有一个数据框，当我将其导出到csv文件时，它看起来就像我想要的那样。
CompanyName 1 2 3 4 5 6 7 8 9 10 11 12
Company 1 182 270 278 314 180 152 110 127 129 117 127 81
Company 2 163 147 192 142 186 231 214 130 112 117 93 101
Company 3 126 88 99 139 97 97 96 37 79 116 111 95
Company 4 84 89 71 95 80 89 83 88 104 93 78 64
但是，当我尝试从'CompanyName'键中取出时，我得到一个KeyError: 'CompanyName'我怀疑它被某处覆盖但我不确定如何修复它。
如果我打印我的数据帧，我得到：
pivot_table.head(2)
Out[62]:
Month 1 2 3 4 5 6 7 8 9 10 11 CompanyName
Company 1 182 270 278 314 180 152 110 127 129 117 127
Company 2 163 147 192 142 186 231 214 130 112 117 93
Month 12
CompanyName
Company 1 81
Company 2 101
这很难读懂，无法分辨出发生了什么。抛出错误的代码：
pivot_table['CompanyName'] = [str(x) for x in pivot_table['CompanyName']]
Companies = list(pivot_table['CompanyName'])
months = ["1","2","3","4","5","6","7","8","9","10","11","12"]
pivot_table = pivot_table.set_index('CompanyName')
修改
Bleh的回答帮助消除了这个KeyError。我需要通过重置索引来启动代码，因为它无法调用之前已成为索引的Key。
答案 0 :(得分：9)
这是因为您已将索引设置为CompanyName。
您无法以这种方式引用索引。
使用pivot_table = pivot_table.reset_index()重置索引并再次尝试访问它。
这是重现的错误：
In [45]: df = pd.read_clipboard()
In [46]: df
Out[46]:
CompanyName 1 2 3 4 5 6 7 8 9 10 11 \
Company 1 182 270 278 314 180 152 110 127 129 117 127
Company 2 163 147 192 142 186 231 214 130 112 117 93
Company 3 126 88 99 139 97 97 96 37 79 116 111
Company 4 84 89 71 95 80 89 83 88 104 93 78
12
Company 81
Company 101
Company 95
Company 64
In [47]: df['CompanyName']
Out[47]:
Company 1
Company 2
Company 3
Company 4
Name: CompanyName, dtype: int64
In [48]: df = df.set_index('CompanyName')
In [49]: df['CompanyName']
---------------------------------------------------------------------------
KeyError Traceback (most recent call last)
<ipython-input-49-d5b597a2bc80> in <module>()
----> 1 df['CompanyName']
/Library/Python/2.7/site-packages/pandas-0.16.1-py2.7-macosx-10.10-intel.egg/pandas/core/frame.pyc in __getitem__(self, key)
1789 return self._getitem_multilevel(key)
1790 else:
-> 1791 return self._getitem_column(key)
1792
1793 def _getitem_column(self, key):
/Library/Python/2.7/site-packages/pandas-0.16.1-py2.7-macosx-10.10-intel.egg/pandas/core/frame.pyc in _getitem_column(self, key)
1796 # get column
1797 if self.columns.is_unique:
-> 1798 return self._get_item_cache(key)
1799
1800 # duplicate columns & possible reduce dimensionaility
/Library/Python/2.7/site-packages/pandas-0.16.1-py2.7-macosx-10.10-intel.egg/pandas/core/generic.pyc in _get_item_cache(self, item)
1082 res = cache.get(item)
1083 if res is None:
-> 1084 values = self._data.get(item)
1085 res = self._box_item_values(item, values)
1086 cache[item] = res
/Library/Python/2.7/site-packages/pandas-0.16.1-py2.7-macosx-10.10-intel.egg/pandas/core/internals.pyc in get(self, item, fastpath)
2849
2850 if not isnull(item):
-> 2851 loc = self.items.get_loc(item)
2852 else:
2853 indexer = np.arange(len(self.items))[isnull(self.items)]
/Library/Python/2.7/site-packages/pandas-0.16.1-py2.7-macosx-10.10-intel.egg/pandas/core/index.pyc in get_loc(self, key, method)
1576 """
1577 if method is None:
-> 1578 return self._engine.get_loc(_values_from_object(key))
1579
1580 indexer = self.get_indexer([key], method=method)
pandas/index.pyx in pandas.index.IndexEngine.get_loc (pandas/index.c:3824)()
pandas/index.pyx in pandas.index.IndexEngine.get_loc (pandas/index.c:3704)()
pandas/hashtable.pyx in pandas.hashtable.PyObjectHashTable.get_item (pandas/hashtable.c:12349)()
pandas/hashtable.pyx in pandas.hashtable.PyObjectHashTable.get_item (pandas/hashtable.c:12300)()
KeyError: 'CompanyName'
更正输出：
In [50]: df = df.reset_index()
In [51]: df['CompanyName']
Out[51]:
0 1
1 2
2 3
3 4
Name: CompanyName, dtype: int64