'dataframe'对象没有属性'str'问题 [英] 'dataframe' object has no attribute 'str' problem

问题描述

我正在尝试删除包含某些字符串的行.但是，我得到了错误:

I am trying to delete rows that contain certain strings. However, I am getting the error:

pandas-'dataframe'对象没有属性'str'错误.

pandas - 'dataframe' object has no attribute 'str' error.

这是我的代码:

df = df[~df['colB'].str.contains('Example:')] 

我该如何解决?

推荐答案

第一个问题应该是重复的列名称，因此在选择colB之后，获取的不是Series，而是DataFrame:

First problem shoud be duplicated columns names, so after select colB get not Series, but DataFrame:

df = pd.DataFrame([['Example: s', 'as', 2], ['dd', 'aaa', 3]], columns=['colB','colB','colC'])
print (df)
         colB colB  colC
0  Example: s   as     2
1          dd  aaa     3

print (df['colB'])
         colB colB
0  Example: s   as
1          dd  aaa

#print (df['colB'].str.contains('Example:'))
#>AttributeError: 'DataFrame' object has no attribute 'str'

解决方案应将列连接在一起:

Solution should be join columns together:

print (df['colB'].apply(' '.join, axis=1))
0    Example: s as
1           dd aaa

df['colB'] = df.pop('colB').apply(' '.join, axis=1)
df = df[~df['colB'].str.contains('Example:')] 
print (df)
   colC    colB
1     3  dd aaa

---

第二个问题应该是hidden MultiIndex:

---

Second problem should be hidden MultiIndex:

df = pd.DataFrame([['Example: s', 'as', 2], ['dd', 'aaa', 3]], columns=['colA','colB','colC'])
df.columns = pd.MultiIndex.from_arrays([df.columns])
print (df)
         colA colB colC
0  Example: s   as    2
1          dd  aaa    3

print (df['colB'])
  colB
0   as
1  aaa

#print (df['colB'].str.contains('Example:'))
#>AttributeError: 'DataFrame' object has no attribute 'str'

解决方案已重新分配至第一级:

Solution is reassign first level:

df.columns = df.columns.get_level_values(0)
df = df[~df['colB'].str.contains('Example:')] 
print (df)
         colA colB  colC
0  Example: s   as     2
1          dd  aaa     3

第三个应该是MultiIndex:

df = pd.DataFrame([['Example: s', 'as', 2], ['dd', 'aaa', 3]], columns=['colA','colB','colC'])
df.columns = pd.MultiIndex.from_product([df.columns, ['a']])
print (df)
         colA colB colC
            a    a    a
0  Example: s   as    2
1          dd  aaa    3

print (df['colB'])
     a
0   as
1  aaa

print (df.columns)
MultiIndex(levels=[['colA', 'colB', 'colC'], ['a']],
           codes=[[0, 1, 2], [0, 0, 0]])

#print (df['colB'].str.contains('Example:'))
#>AttributeError: 'DataFrame' object has no attribute 'str'

解决方案是通过tuple选择MultiIndex:

df1 = df[~df[('colB', 'a')].str.contains('Example:')] 
print (df1)
         colA colB colC
            a    a    a
0  Example: s   as    2
1          dd  aaa    3

或重新分配:

df.columns = df.columns.get_level_values(0)
df2 = df[~df['colB'].str.contains('Example:')] 
print (df2)
         colA colB  colC
0  Example: s   as     2
1          dd  aaa     3

或删除第二级:

df.columns = df.columns.droplevel(1)
df2 = df[~df['colB'].str.contains('Example:')] 
print (df2)
         colA colB  colC
0  Example: s   as     2
1          dd  aaa     3

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