重写csv某行

import csv
to_path="1.csv"
to_path_="1的备份最终用这个文件.csv"

with open(to_path, 'r') as f1:
    read_it = csv.reader(f1)
    show_rows = [row for row in read_it]

for i in show_rows:
    if i[0]=="ttt":   # 如果第一列 的值等于 "ttt" 就重写
        os.remove(to_path_)  #删掉预留的重写文件
        re_write=[i[0], i[1],i[2],i[3],i[4],"8881"]  #标记要重写的内容
        with open(to_path, 'r', newline='') as f_old, \
                open(to_path_, 'w', newline='') as f_new:
            f_csv_old = csv.reader(f_old)
            f_csv_new = csv.writer(f_new)
            for iw, rows in enumerate(f_csv_old):  # 重写header
                if iw == 0:
                    f_csv_new.writerow(rows)
                    break
            for rows in f_csv_old:
                if rows[0] != "ttt":  # 第一列值为ttt的行 不进行重写
                    f_csv_new.writerow(rows)
            f_csv_new.writerow(re_write)  # 重写标记的行
    else:
        pass