import pandas as pd
def get_under_rolling(df,window,user,name):
df[name] = df[user].iloc[::-1].rolling(window=window).apply(lambda x:x[0]).iloc[::-1]
return df
if __name__ == '__main__':
df = pd.DataFrame({'a':[1,2,3,4,5],
'b':[2,3,4,5,6]})
# 把b列向下取值作为新的c列
df = get_under_rolling(df, window=3, user='b',name='c')
原始df
新的df