正文
pandas 索引与列相互转化
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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
