pandas.hashtable.PyObjectHashTable.get_item 中的 Python 熊猫 groupby 键错误
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Python pandas groupby key error in pandas.hashtable.PyObjectHashTable.get_item
提问by RedRaven
I am doing what seems to be a simple group by in Pandas. The column is a string column with no NaN's or weird strings. However, I keep getting the below error. Does anyone know why this mights happen? I feel like it may have something to do with my data, but it all seems to be ok...
我在 Pandas 中做的似乎是一个简单的组。该列是一个字符串列，没有 NaN 或奇怪的字符串。但是，我不断收到以下错误。有谁知道为什么会发生这种情况？我觉得这可能与我的数据有关，但似乎一切正常......
I am running by_user = df.groupby('User')
我在跑步 by_user = df.groupby('User')
and the stack trace:
和堆栈跟踪：
by_user = df.groupby('User')
File "c:\Anaconda\lib\site-packages\pandas\core\generic.py", line 2773, in groupby
sort=sort, group_keys=group_keys, squeeze=squeeze)
File "c:\Anaconda\lib\site-packages\pandas\core\groupby.py", line 1142, in groupby
return klass(obj, by, **kwds)
File "c:\Anaconda\lib\site-packages\pandas\core\groupby.py", line 388, in __init__ level=level, sort=sort)
File "c:\Anaconda\lib\site-packages\pandas\core\groupby.py", line 2041, in _get_grouper
gpr = obj[gpr]
File "c:\Anaconda\lib\site-packages\pandas\core\frame.py", line 1678, in __getitem__
return self._getitem_column(key)
File "c:\Anaconda\lib\site-packages\pandas\core\frame.py", line 1685, in _get item_column
return self._get_item_cache(key)
File "c:\Anaconda\lib\site-packages\pandas\core\generic.py", line 1052, in _ge
t_item_cache
values = self._data.get(item)
File "c:\Anaconda\lib\site-packages\pandas\core\internals.py", line 2565, in get
loc = self.items.get_loc(item)
File "c:\Anaconda\lib\site-packages\pandas\core\index.py", line 1181, in get_loc
return self._engine.get_loc(_values_from_object(key))
File "index.pyx", line 129, in pandas.index.IndexEngine.get_loc (pandas\index.
c:3656)
File "index.pyx", line 149, in pandas.index.IndexEngine.get_loc (pandas\index.
c:3534)
File "hashtable.pyx", line 696, in pandas.hashtable.PyObjectHashTable.get_item
(pandas\hashtable.c:11911)
File "hashtable.pyx", line 704, in pandas.hashtable.PyObjectHashTable.get_item
(pandas\hashtable.c:11864)
KeyError: 'User'
df.info():
df.info():
User Code 175167 non-null object
Version 175167 non-null object
Date Accessed 175167 non-null datetime64[ns]
Series 175167 non-null object
Software 175167 non-null object
User 175167 non-null object
回答by DSM
[moved from comments]
[移自评论]
It's easy to miss trailing whitespace in column names, but you can check df.columnsmanually:
列名中很容易遗漏尾随空格，但您可以df.columns手动检查：
>>> df = pd.DataFrame({"User": [1,2]})
>>> df2 = pd.DataFrame({"User ": [1,2]})
>>> df
User
0 1
1 2
>>> df2
User
0 1
1 2
>>> df.columns
Index([u'User'], dtype='object')
>>> df2.columns
Index([u'User '], dtype='object')
(To peel back the curtain a bit, I suspected something like this might be going on because when I mocked up my own DataFrame and looked at df.info(), I didn't see as much space between the column names and the numbers as your output seemed to show.)
（稍微揭开帷幕，我怀疑可能会发生这样的事情，因为当我模拟自己的 DataFrame 并查看 时df.info()，我没有看到列名和数字之间的空间与您的输出看起来一样大展示。）
