pandas-数据规整(3) -- 数据重构stack、unstack

最外层level=0
最里面那层level可以是-1也可以是1.

import pandas as pd
# 创建dataframe
header = pd.MultiIndex.from_product([['Semester1','Semester2'],['Maths','Science']])
d = [[12,45,67,56],[78,89,45,67],[45,67,89,90],[67,44,56,55]]
 
df = pd.DataFrame(d, index=['Alisa','Bobby','Cathrine','Jack'], columns=header)
df

stacked_df = df.stack()
stacked_df

# level 参数
df.stack(level=0)

df.stack(level=-1)

stacked_df.unstack()

stacked_df.unstack(level=0)