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CSV__04--python使用迭代器读取csv文件出现读取结果为空的解决办法

 1 year ago
source link: https://blog.51cto.com/husheng/5918791
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Table of Contents

1 迭代器的概念

迭代器（iterator）有时又称光标（cursor）是程序设计的软件设计模式，可在容器对象（container，例如链表或数组）上遍访的接口。

2 迭代器的特点

  • 强制性：必须将元素从迭代器中取出后，才能使用元素；
  • 一次性：取出以后该元素就从迭代器中删除，无法二次遍历；
  • 未知性：容器内部元素无法直接定位，只能遍历按序取出。

3 问题解决

迭代器每次使用后会迭代至末尾

当我们再次使用这个迭代器进行for循环读取时得到的结果自然为空

解决方法只需新建一个迭代器即可。

迭代器：IndexError: list index out of range

import csv

#读T1
reader = csv.reader(open('结果1.csv','rt'))
column1 = [row1[0:9] for row1 in reader]
# 写入标题
with open('demo2.csv', 'w', encoding='UTF8', newline='') as f0:
    writer0 = csv.writer(f0)
    # write the header
    writer0.writerow(column1[0])

#读T2
reader2 = csv.reader(open('结果1.csv', 'rt'))
column2 = [row2[0:3]+row2[9:15] for row2 in reader2]

#读T3
reader3 = csv.reader(open('结果1.csv', 'rt'))
column3 = [row3[0:3]+row3[15:21] for row3 in reader3]

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