【Python】：利用rolling和apply函数的向下取值

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