Python 数据帧中的关键错误
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KeyError in Dataframe
提问by jenryb
I have a dataframe that looks just how I want it when I export it to a csv file.
我有一个数据框，当我将它导出到 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
However, when I try to pull from the key 'CompanyName' I get a KeyError: 'CompanyName'I suspect it's being overwritten somewhere but I'm not sure how to fix it.
但是，当我尝试从密钥“公司名称”中提取时，KeyError: 'CompanyName'我怀疑它在某处被覆盖，但我不确定如何修复它。
if I print my dataframe I get:
如果我打印我的数据框，我会得到：
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
which is rather hard to read to be able to tell what's going on. The code that is throwing the error:
这是相当难以阅读的，以便能够说出正在发生的事情。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')
EDIT
编辑
Bleh's answer helped eliminate this KeyError. I needed to start the code by resetting the index, because it couldn't call a Key that had been made an index earlier.
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创建索引的 Key。
采纳答案by kennes
This is because you've set the index to CompanyName.
这是因为您已将索引设置为CompanyName.
You cannot reference the index in that manner.
您不能以这种方式引用索引。
Use pivot_table = pivot_table.reset_index()to reset the index and try accessing it again.
使用pivot_table = pivot_table.reset_index()重置索引并再次尝试访问它。
Here's the reproduced error:
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'
Correction Output:
校正输出：
In [50]: df = df.reset_index()
In [51]: df['CompanyName']
Out[51]:
0 1
1 2
2 3
3 4
Name: CompanyName, dtype: int64
