Pandas Multiindex从给定级别选择列列表

Question

如果我像这样制作多索引列数据框：

iterables = [['bar', 'baz', 'foo', 'qux'], ['one', 'two']]
index = pd.MultiIndex.from_product(iterables, names=['first', 'second'])
df = pd.DataFrame(np.random.randn(3, 8), index=['A', 'B', 'C'], columns=index)


first        bar                 baz                 foo                 qux  \
second       one       two       one       two       one       two       one   
A      -0.119687 -0.518318  0.113920 -1.028505  1.106375 -1.020139 -0.039300   
B       0.123480 -2.091120  0.464597 -0.147211 -0.489895 -1.090659 -0.592679   
C      -1.174376  0.282011 -0.197658 -0.030751  0.117374  1.591109  0.796908   

first             
second       two  
A      -0.938209  
B      -0.851483  
C       0.442621  

我想使用列表仅从第一组列中选择列，

select_cols=['bar', 'qux']

这样结果将是：

first        bar                  qux  
second       one       two        one        two
A      -0.119687 -0.518318  -0.039300  -0.938209    
B       0.123480 -2.091120  -0.592679  -0.851483    
C      -1.174376  0.282011   0.796908   0.442621  

我将如何去做？（提前感谢）

Answer 1

简单的列选择也可以：

df[['bar', 'qux']]

# first        bar                 qux          
# second       one       two       one       two
# A       0.651522  0.480115 -2.924574  0.616674
# B      -0.395988  0.001643  0.358048  0.022727
# C      -0.317829  1.400970 -0.773148  1.549135