JAVA高级面试进阶训练营视频教程

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###df_18的字段fuek是否包含 / 
df_18[df_18['fuel'].str.contains('/')]

报错:

ValueError Traceback (most recent call last)
in ()
1 # 检查是否已删除
----> 2 df_18[df_18['fuel'].str.contains('/')]

/opt/conda/lib/python3.6/site-packages/pandas/core/frame.py in getitem(self, key)
1956 if isinstance(key, (Series, np.ndarray, Index, list)):
1957 # either boolean or fancy integer index
-> 1958 return self.getitemarray(key)
1959 elif isinstance(key, DataFrame):
1960 return self.getitemframe(key)

/opt/conda/lib/python3.6/site-packages/pandas/core/frame.py in getitemarray(self, key)
1983 def getitemarray(self, key):
1984 # also raises Exception if object array with NA values
-> 1985 if com.is_bool_indexer(key):
1986 # warning here just in case -- previously setitem was
1987 # reindexing but getitem was not; it seems more reasonable to

/opt/conda/lib/python3.6/site-packages/pandas/core/common.py in is_bool_indexer(key)
187 if not lib.is_bool_array(key):
188 if isnull(key).any():
--> 189 raise ValueError('cannot index with vector containing '
190 'NA / NaN values')
191 return False

ValueError: cannot index with vector containing NA / NaN values

原因:

fuel 中存在 NaN 值，所以得到的结果也是缺失值，而缺失值是不能直接作为索引的。你可以考虑在 contains 中更改 na 参数值，让其变为 False——Series.str.contains(pat, case=True, flags=0, na=nan, regex=True)

解决:

你可以考虑在 contains 中更改 na 参数值，让其变为 False——Series.str.contains(pat, case=True, flags=0, na=nan, regex=True)
case是False是不区分大小写，而na=False 或 nan是不是有NaN来填充缺失值。
如果这种方法不能解决:先将df_18的空值删除再进行正则化匹配
　　df_18 = df_18.dropna(how='any')