pandas 如何处理 KeyError：“['blah'] 不在索引中”
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How to handle KeyError: "['blah'] not in index"
提问by Mike
I'm looking at the US names dataset (SSA), as described in Python for Data Analysis by Wes McKinney.
我正在查看美国名称数据集 (SSA)，如 Wes McKinney 在 Python for Data Analysis 中所述。
This works:
这有效：
total_births = top1000.pivot_table('births', index = 'year', columns = 'name', aggfunc = sum)
subset = total_births[['Michael', 'Mike', 'Martin']].fillna(0)
subset.plot( title = 'Number of births per year', grid = True, figsize=(28,20), xticks=range(1880, 2020, 5)).get_figure().savefig('output2.png', bbox_inches = 'tight')
But when I add an unpopular name, which nevertheless is in the data set:
但是当我添加一个不受欢迎的名字时，它仍然在数据集中：
subset = total_births[['Michael', 'Mike', 'Martin', 'Ammar']].fillna(0)
...I get the following error:
...我收到以下错误：
Traceback (most recent call last):
File "names.py", line 44, in <module>
subset = total_births[['Michael', 'Mike', 'Martin', 'Ammar']].fillna(0)
File "/home/mike/anaconda/lib/python2.7/site-packages/pandas/core/frame.py", line 1774, in __getitem__
return self._getitem_array(key)
File "/home/mike/anaconda/lib/python2.7/site-packages/pandas/core/frame.py", line 1818, in _getitem_array
indexer = self.ix._convert_to_indexer(key, axis=1)
File "/home/mike/anaconda/lib/python2.7/site-packages/pandas/core/indexing.py", line 1143, in _convert_to_indexer
raise KeyError('%s not in index' % objarr[mask])
KeyError: "['Ammar'] not in index"
I tried adding fillna(0), but it doesn't help... The code is available at https://github.com/m1key/data-science-sandbox(ade55154f177410e1e269d64766a4e8b8e1ae585), the troublesome lines are commented out.
我尝试添加fillna(0)，但没有帮助...代码可在https://github.com/m1key/data-science-sandbox(ade55154f177410e1e269d64766a4e8b8e1ae585) 获得，麻烦的行已注释掉。
Sample data set:
样本数据集：
name Aaden Aaliyah Aanya Aarav Aaron Aarush Ab Abagail Abb Abbey \
year
1880 NaN NaN NaN NaN 102 NaN NaN NaN NaN NaN
1881 NaN NaN NaN NaN 94 NaN NaN NaN NaN NaN
1882 NaN NaN NaN NaN 85 NaN NaN NaN NaN NaN
1883 NaN NaN NaN NaN 105 NaN NaN NaN NaN NaN
1884 NaN NaN NaN NaN 97 NaN NaN NaN NaN NaN
name ... Zoa Zoe Zoey Zoie Zola Zollie Zona Zora Zula Zuri
year ...
1880 ... 8 23 NaN NaN 7 NaN 8 28 27 NaN
1881 ... NaN 22 NaN NaN 10 NaN 9 21 27 NaN
1882 ... 8 25 NaN NaN 9 NaN 17 32 21 NaN
1883 ... NaN 23 NaN NaN 10 NaN 11 35 25 NaN
1884 ... 13 31 NaN NaN 14 6 8 58 27 NaN
Thanks for any hints.
感谢您的任何提示。
回答by Julien Marrec
Ammar doesn't appear to be in your dataset.
Ammar 似乎不在您的数据集中。
In order to double check, try 'Ammar' in total_births.columnswhich will return a boolean (Trueor False)
为了仔细检查，尝试'Ammar' in total_births.columns哪个将返回一个布尔值（True或False）
