pandas 索引与列相互转化

1. 准备数据

import pandas as pd
from io import StringIO


csv_txt = '''"date","player1","player2","score1","score2"
"2017-06-05","张继科","林思远",3,2
"2017-06-06","丁宁","刘思文",3,0
"2017-06-07","马琳","樊振东",2,3
"2017-06-08","张燕","丁宁",0,3
"2017-06-09","张继科","马琳",3,2
"2017-06-10","刘思文","张燕",4,1
"2017-06-11","马琳","林思远",3,2
'''

#df = pd.read_csv(StringIO(csv_txt), header=0, index_col="date") # 以 date 作为 index

df = pd.read_csv(StringIO(csv_txt), header=0) # 默认 index

2. 列 ——> 索引

• df.set_index('date')

df.set_index('date', inplace=True) # column 改为 index

3. 索引 ——> 列

• df['index'] = df.index
• df.reset_index(level=0, inplace=True)
• df.reset_index(level=['tick', 'obs'])
• df['si_name'] = df.index.get_level_values('si_name') # where si_name is the name of the subindex.

df.reset_index() # （all）index 改为 column

#df.reset_index(level=0, inplace=True) # （the first）index 改为 column