在 Pandas 中切片时出现值错误

Question

我有一个 DataFrame，我想使用 'str.contrains()' 方法。当我阅读pandas + dataframe - select by partial string 时，我相信我已经找到了如何做到这一点。但是，我不断收到值错误。

我的DataFrame如下：

ID,ENROLLMENT_DATE,TRAINER_MANAGING,TRAINER_OPERATOR,FIRST_VISIT_DATE
1536D,12-Feb-12,"06DA1B3-Lebanon NH",,15-Feb-12
F15D,18-May-12,"06405B2-Lebanon NH",,25-Jul-12
8096,8-Aug-12,"0643D38-Hanover NH","0643D38-Hanover NH",25-Jun-12
A036,1-Apr-12,"06CB8CF-Hanover NH","06CB8CF-Hanover NH",9-Aug-12
8944,19-Feb-12,"06D26AD-Hanover NH",,4-Feb-12
1004E,8-Jun-12,"06388B2-Lebanon NH",,24-Dec-11
11795,3-Jul-12,"0649597-White River VT","0649597-White River VT",30-Mar-12
30D7,11-Nov-12,"06D95A3-Hanover NH","06D95A3-Hanover NH",30-Nov-11
3AE2,21-Feb-12,"06405B2-Lebanon NH",,26-Oct-12
B0FE,17-Feb-12,"06D1B9D-Hartland VT",,16-Feb-12
127A1,11-Dec-11,"064456E-Hanover NH","064456E-Hanover NH",11-Nov-12
161FF,20-Feb-12,"0643D38-Hanover NH","0643D38-Hanover NH",3-Jul-12
A036,30-Nov-11,"063B208-Randolph VT","063B208-Randolph VT",
475B,25-Sep-12,"06D26AD-Hanover NH",,5-Nov-12
151A3,7-Mar-12,"06388B2-Lebanon NH",,16-Nov-12
CA62,3-Jan-12,,,
D31B,18-Dec-11,"06405B2-Lebanon NH",,9-Jan-12
20F5,8-Jul-12,"0669C50-Randolph VT",,3-Feb-12
8096,19-Dec-11,"0649597-White River VT","0649597-White River VT",9-Apr-12
14E48,1-Aug-12,"06D3206-Hanover NH",,
177F8,20-Aug-12,"063B208-Randolph VT","063B208-Randolph VT",5-May-12
553E,11-Oct-12,"06D95A3-Hanover NH","06D95A3-Hanover NH",8-Mar-12
12D5F,18-Jul-12,"0649597-White River VT","0649597-White River VT",2-Nov-12
C6DC,13-Apr-12,"06388B2-Lebanon NH",,
11795,27-Feb-12,"0643D38-Hanover NH","0643D38-Hanover NH",19-Jun-12
17B43,11-Aug-12,,,22-Oct-12
A036,11-Aug-12,"06D3206-Hanover NH",,19-Jun-12

然后我运行以下代码：

test = pandas.read_csv('testcsv.csv')
test[test.TRAINER_MANAGING.str.contains('Han', na=False)]

我收到以下错误：

---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-54-e0c4624c9346> in <module>()
----> 1 test[test.TRAINER_MANAGING.str.contains('Han', na=False)]

.virtualenvs/ipython/lib/python2.7/site-packages/pandas/core/frame.pyc in __getitem__(self, key)
   1958 
   1959             # also raises Exception if object array with NA values
-> 1960             if com._is_bool_indexer(key):
   1961                 key = np.asarray(key, dtype=bool)
   1962             return self._getitem_array(key)

.virtualenvs/ipython/lib/python2.7/site-packages/pandas/core/common.pyc in _is_bool_indexer(key)
    685         if not lib.is_bool_array(key):
    686             if isnull(key).any():
--> 687                 raise ValueError('cannot index with vector containing '
    688                                  'NA / NaN values')
    689             return False

ValueError: cannot index with vector containing NA / NaN values

我觉得我错过了一些简单的东西。任何帮助，将不胜感激。

Answer 1

您的字符串搜索仍会返回 nan 值，而切片操作仅适用于布尔值。 'na=False' 似乎不起作用（在这种情况下？），我可以使用最新（已发布）Pandas 版本在我的机器上复制它。

您可以通过首先将 .fillna() 函数应用于以下结果来解决此问题：

test[test.TRAINER_MANAGING.str.contains('Han').fillna(False)]

返回：

       ID ENROLLMENT_DATE    TRAINER_MANAGING    TRAINER_OPERATOR FIRST_VISIT_DATE
2    8096        8-Aug-12  0643D38-Hanover NH  0643D38-Hanover NH        25-Jun-12
3    A036        1-Apr-12  06CB8CF-Hanover NH  06CB8CF-Hanover NH         9-Aug-12
4    8944       19-Feb-12  06D26AD-Hanover NH                 NaN         4-Feb-12
7    30D7       11-Nov-12  06D95A3-Hanover NH  06D95A3-Hanover NH        30-Nov-11
10  127A1       11-Dec-11  064456E-Hanover NH  064456E-Hanover NH        11-Nov-12
11  161FF       20-Feb-12  0643D38-Hanover NH  0643D38-Hanover NH         3-Jul-12
13   475B       25-Sep-12  06D26AD-Hanover NH                 NaN         5-Nov-12
19  14E48        1-Aug-12  06D3206-Hanover NH                 NaN              NaN
21   553E       11-Oct-12  06D95A3-Hanover NH  06D95A3-Hanover NH         8-Mar-12
24  11795       27-Feb-12  0643D38-Hanover NH  0643D38-Hanover NH        19-Jun-12
26   A036       11-Aug-12  06D3206-Hanover NH                 NaN        19-Jun-12

我以前从未使用过 str.contains 函数，所以我不确定它是否不能正常工作。如果它应该像您的示例一样工作，我们应该在 github 上打开一个问题。