pandas-shift、stack

df.shift

s=pd.Series([1,3,5,np.nan,6,8],index=pd.date_range('20201010',periods=6))
s.shift(2) #将前2行变为NaN

 df.stack

#将列索引变成行索引

tuples = list(zip(*[['bar','bar','baz','baz','foo','foo'],['one','two','one','two','one','two']]))
index = pd.MultiIndex.from_tuples(tuples,names=['first','second'])
df = pd.DataFrame(np.random.randn(6,2),index = index,columns=['A','B'])
stack = df.stack()  #将列索引变成行索引
stack.reset_index() #重新索引
stack.unstack()  #还原