pandas-data regularization (3) - data reconstruction stack, unstack

The outermost level = 0,
the innermost level can be -1 or 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)