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
# =============================================================================