不排序的Pandas MultiIndex切片

import pandas as pd

# 创建一个MultiIndex DataFrame
arrays = [
    ['North', 'North', 'South', 'South'],
    [2019, 2020, 2019, 2020]
]
index = pd.MultiIndex.from_arrays(arrays, names=('Region', 'Year'))
df = pd.DataFrame({'Sales': [100, 150, 200, 250]}, index=index)

print(df)

              Sales
Region Year       
North  2019     100
       2020     150
South  2019     200
       2020     250

# 获取特定区域和年份的数据
north_2019_sales = df.xs((('North', 2019)), level=['Region', 'Year'])
print(north_2019_sales)

Sales    100
Name: (North, 2019), dtype: int64

# 直接通过索引访问
north_2020_sales = df.loc[('North', 2020), 'Sales']
print(north_2020_sales)

150

df_sorted = df.sort_index()

north_sales_2019 = df_sorted.xs(2019, level='Year').loc['North']
print(north_sales_2019)

Sales    100
Name: (North, 2019), dtype: int64