递归
def df_merge(self, df_lst): df_len = len(df_lst) if df_len == 1: return df_lst[0] elif df_len == 2: return df_lst[0].merge(df_lst[1], on=["company", "site_id", "site_name"], how="right") else: return self.df_merge(df_lst[0:df_len-1]).merge(df_lst[df_len-1], on=["company", "site_id", "site_name"], how="right")