import numpy as np
import pandas as pd
from pandas import Series,DataFrame
df = DataFrame(np.arange(12).reshape((4,3)),
                 index = [['a','a','b','b'],[1,2,1,2]],
                 columns = [['Ohio','Ohio','Colorado'],['Green','Red','Green']])
df.index.names = ['key1','key2']
df.columns.names = ['state'
 
,'color']
print(df)

state      Ohio     Colorado
color     Green Red    Green
key1 key2                   
a    1        0   1        2
     2        3   4        5
b    1        6   7        8
     2        9  10       11

一、調整多級索引間的順序

print(df.swaplevel('key1','key2'))

state      Ohio     Colorado
color     Green Red    Green
key2 key1                   
1    a        0   1        2
2    a        3   4        5
1    b        6   7        8
2    b        9  10       11
 

二、對某級別索引排序

print(df.sort_index(level=1))

state      Ohio     Colorado
color     Green Red    Green
key1 key2                   
a    1        0   1        2
b    1        6   7        8
a    2        3   4        5
b    2        9  10       11

三、根據某級別索引進行彙總

print(df.sum(level='color',axis=1
 
))

color      Green  Red
key1 key2            
a    1         2    1
     2         8    4
b    1        14    7
     2        20   10

四、指定DataFrame的列為索引

data = {'種類':['蘋果','梨','草莓'],
    '數量':[3,2,5],
       '價格':[10,9,8]}
df = DataFrame(data)

指定

df = df.set_index('種類')
print(df)

    價格  數量
種類        
蘋果  10   3
梨    9   2
草莓   8   5

還原

print(df.reset_index())

   種類  價格  數量
0  蘋果  10   3
1   梨   9   2
2  草莓   8   5