如何剪切部分文本并用Python和RegEx替换每一行

Question

你好，我是Python的初学者，刚刚开始学习Python并使用RegEx进行文本操作。 如果我违反了StackOverflow的一些规则，我会提前道歉

我正在用Python编写一个脚本，从第一行开始（剪切）日期和时间，并在每一行上替换“date”“TimeWindowStart”和“TimeWindowEnd”

ReportDate=03/24/2019, TimeWindowStart=18:00:00, TimeWindowEnd=20:59:59

Date, TimeWindowStart, TimeWindowEnd, Report-20190323_210000
Date, TimeWindowStart, TimeWindowEnd, Report-20190323_210000
Date, TimeWindowStart, TimeWindowEnd, Report-20190323_210000
Date, TimeWindowStart, TimeWindowEnd, Report-20190323_210000
Date, TimeWindowStart, TimeWindowEnd, Report-20190323_210000
Date, TimeWindowStart, TimeWindowEnd, Report-20190323_210000
Date, TimeWindowStart, TimeWindowEnd, Report-20190323_210000

我知道如何选择与正则表达式日期

([0-9][0-9]|2[0-9])/[0-9][0-9](/[0-9][0-9][0-9][0-9])?

如何选择时间

([0-9][0-9]|2[0-9]):[0-9][0-9](:[0-9][0-9])?

但是我一直在思考如何选择文本的一部分，复制它，然后找到我想用替换的文本回复sub功能

所以最终输出如下所示：

ReportDate=, TimeWindowStart=, TimeWindowEnd=

03/24/2019, 18:00:00, 20:59:59, Report-20190323_210000
03/24/2019, 18:00:00, 20:59:59, Report-20190323_210000
03/24/2019, 18:00:00, 20:59:59, Report-20190323_210000
03/24/2019, 18:00:00, 20:59:59, Report-20190323_210000 
03/24/2019, 18:00:00, 20:59:59, Report-20190323_210000 
03/24/2019, 18:00:00, 20:59:59, Report-20190323_210000 
03/24/2019, 18:00:00, 20:59:59, Report-20190323_210000

Answer 1

首先，您可以在regex查询中指定一个量词，因此如果您想要4个数字，您不需要[0-9][0-9][0-9][0-9]，但可以使用[0-9]{4}。要捕获表达式，请将其包装在圆括号中value=([0-9]{4})将只提供数字

如果你想使用re.sub，你只需要给它一个模式，一个替换字符串和你的输入字符串，例如re.sub(pattern, replacement, string)

因此：

import re

txt = """ReportDate=03/24/2019, TimeWindowStart=18:00:00, TimeWindowEnd=20:59:59

Date, TimeWindowStart, TimeWindowEnd, Report-20190323_210000
Date, TimeWindowStart, TimeWindowEnd, Report-20190323_210000
Date, TimeWindowStart, TimeWindowEnd, Report-20190323_210000
Date, TimeWindowStart, TimeWindowEnd, Report-20190323_210000
Date, TimeWindowStart, TimeWindowEnd, Report-20190323_210000
Date, TimeWindowStart, TimeWindowEnd, Report-20190323_210000
Date, TimeWindowStart, TimeWindowEnd, Report-20190323_210000
"""

pattern_date = 'ReportDate=([0-9]{2}/[0-9]{2}/[0-9]{4})'
report_date = re.findall(pattern_date, txt)[0]

pattern_time_start = 'TimeWindowStart=([0-9]{2}:[0-9]{2}:[0-9]{2})'
start_time = re.findall(pattern_time_start, txt)[0]

pattern_time_end = 'TimeWindowEnd=([0-9]{2}:[0-9]{2}:[0-9]{2})'
end_time = re.findall(pattern_time_end, txt)[0]

splitted = txt.split('\n')  # Split the txt so that we skip the first line

txt2 = '\n'.join(splitted[1:])  # text to perform the sub 

# substitution of your values
txt2 = re.sub('Date', report_date, txt2)
txt2 = re.sub('TimeWindowStart', start_time, txt2)
txt2 = re.sub('TimeWindowEnd', end_time, txt2)

txt_final = splitted[0] + '\n' + txt2
print(txt_final)

输出：

ReportDate=03/24/2019, TimeWindowStart=18:00:00, TimeWindowEnd=20:59:59

03/24/2019, 18:00:00, 20:59:59, Report-20190323_210000
03/24/2019, 18:00:00, 20:59:59, Report-20190323_210000
03/24/2019, 18:00:00, 20:59:59, Report-20190323_210000
03/24/2019, 18:00:00, 20:59:59, Report-20190323_210000
03/24/2019, 18:00:00, 20:59:59, Report-20190323_210000
03/24/2019, 18:00:00, 20:59:59, Report-20190323_210000
03/24/2019, 18:00:00, 20:59:59, Report-20190323_210000