pandas的set_index和reset_index方法

import pandas as pd
       
data = pd.DataFrame(np.arange(1,10).reshape(3,3),index=["a","b","c"],columns=["A","B","C"])

# =============================================================================
# Out[13]: 
#    A  B  C
# a  1  2  3
# b  4  5  6
# c  7  8  9
# =============================================================================
 

data.set_index("A")   
       
# =============================================================================
# Out[14]: 
#    B  C
# A      
# 1  2  3
# 4  5  6
# 7  8  9       
# =============================================================================

#将A和C的列变成行索引，层次化索引
data.set_index(["A","C"])
      
# =============================================================================
# Out[17]: 
#      B
# A C   
# 1 3  2
# 4 6  5
# 7 9  8        
# =============================================================================
 
data = pd.DataFrame(np.arange(1,10).reshape(3,3),index=["a","b","c"],columns=["A","B","C"])
data.set_index(["C"])      

# =============================================================================
# Out[19]: 
#    A  B
# C      
# 3  1  2
# 6  4  5
# 9  7  8        
# =============================================================================
        
data.reset_index()

# =============================================================================
# Out[24]: 
#   index  A  B  C
# 0     a  1  2  3
# 1     b  4  5  6
# 2     c  7  8  9
# =============================================================================