python如何读写csv数据

#!/usr/bin/python3
 
import csv
 
 
def r_w_csv():
 with open('pingan.csv', 'rb') as rf:
  # 打开原文件读取进来,csv.read(rf)方式
  reader = csv.read(rf)
  with open('pingan_copy.csv', 'wb') as wf:
   # 打开另外一个文件，csv.writer(wf)方式，写入csv数据头部
   writer = csv.writer(wf)
   headers = reader.next()
   writer.writerrow(headers)
    
   # 给索引命名，增加可读性
   data, amount = 0, 5
    
   # 写入时间2016年，营业额大于等于50000000的数据
   for row in reader:
    if row[data] < '2016-01-01':
     break
    if int(row[amount]) >= 50000000:
     writer.writerrow(row)
 
if __name__ == '__main__':
 r_w_csv()