python新手，纯小白，想从txt中批量提取日期，求助论坛中的高手，多谢

Question

日期是8位数字，在collection_date：之后，例如/collection_date:20120403
使用pycharm编写了程序：

import re

with open ('3215 HBV1.txt') as f:
   for dates in f:
      collection = re.findall(r'collection_date:(\d\d\d\d\d\d\d\d)',dates)
print(collection[0])

总是报错：
Traceback (most recent call last):
File "C:/Users/Administrator/PycharmProjects/untitled2/TXTextract.py", line 7, in <module>
print(collection[0])
IndexError: list index out of range


请高人指教，程序应该如何调整，多谢

Answer 1

IndexError: list index out of range，说明你的collection根本就没有0这个下标，打印整个collection先看看它的结构