如何剪切部分文本并用 Python 和 RegEx 替换每一行答案

【问题标题】：How to cut part of the text and replace each line with Python and RegEx如何剪切部分文本并用 Python 和 RegEx 替换每一行
【发布时间】：2019-03-27 15:09:31
【问题描述】：

您好，我是 Python 的初学者，刚刚开始学习它并使用 RegEx 进行文本操作。如果我违反了 StackOverflow 的一些规则，我很抱歉

我正在用 Python 编写一个脚本，我将从第一行获取（剪切）日期和时间，并在每一行替换“日期”“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

我知道如何使用正则表达式日期进行选择

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

以及如何选择时间

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

但我坚持如何选择部分文本复制它然后找到我想用 re.sub 函数替换的文本

所以最终的输出应该是这样的：

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

【问题讨论】：

标签： python regex

【解决方案1】：

首先，您可以在正则表达式查询中指定一个量词，因此如果您需要 4 个数字，则不需要 [0-9][0-9][0-9][0-9]，但您可以使用 [0-9]{4}。要捕获表达式，请将其括在圆括号中 value=([0-9]{4}) 只会给您数字

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

【讨论】：

谢谢@dzang，这对我帮助很大！
@krcha 很高兴听到这个消息。祝你任务顺利！如果您对给出的答案之一感到满意，最好将其标记为已接受的答案。欢呼

【解决方案2】：

这是一个部分答案，因为我不太了解用于处理文本文件的 Python API。您可以阅读文件的第一行，并提取报告日期和开始/结束窗口时间的值。

first = "ReportDate=03/24/2019, TimeWindowStart=18:00:00, TimeWindowEnd=20:59:59"
ReportDate = re.sub(r'ReportDate=([^,]+),.*', '\\1', first)
TimeWindowStart = re.sub(r'.*TimeWindowStart=([^,]+),.*', '\\1', first)
TimeWindowEnd = re.sub(r'.*TimeWindowEnd=(.*)', '\\1', first)

写出第一行，去掉三个变量的值。

然后，您需要做的就是在随后的每一行中读取并执行以下替换：

line = "Date, TimeWindowStart, TimeWindowEnd, Report-20190323_210000"
line = re.sub(r'\bDate\b', ReportDate, line)
line = re.sub(r'\b TimeWindowStart\b', TimeWindowStart, line)
line = re.sub(r'\ TimeWindowEnd\b', TimeWindowEnd, line)

这样处理完每一行，就可以写入输出文件了。

【讨论】：

【解决方案3】：

这是我的代码：

import re

s = """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"""

datereg = r'(\d{2}/\d{2}/\d{4})'
timereg = r'(\d{2}:\d{2}:\d{2})'

dates = re.findall(datereg, s)
times = re.findall(timereg, s)

# replacing one thing at a time
result = re.sub(r'\bDate\b', dates[0],
            re.sub(r'\bTimeWindowEnd\b,', times[1] + ',',
                re.sub(r'\bTimeWindowStart\b,', times[0] + ',',
                    re.sub(timereg, '', 
                        re.sub(datereg, '', s)))))

print(result)

输出：

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

【讨论】：

【解决方案4】：

试试这个，

import re

#Open file and read line by line
with open("a") as file:
 # Get and process first line
 first_line = file.readline()
 m = re.search("ReportDate=(?P<ReportDate>[0-9/]+), TimeWindowStart=(?P<TimeWindowStart>[0-9:]+), TimeWindowEnd=(?P<TimeWindowEnd>[0-9:]+)",first_line)
 first_line= re.sub(m.group('ReportDate'), "", first_line)
 first_line= re.sub(m.group('TimeWindowStart'), "", first_line)
 first_line= re.sub(m.group('TimeWindowEnd'), "", first_line)
 print(first_line)

 # Process rest of the lines
 for line in file:
    line = re.sub(r'\bDate\b', m.group('ReportDate'), line)
    line = re.sub(r'\bTimeWindowStart\b', m.group('TimeWindowStart'), line)
    line = re.sub(r'\bTimeWindowEnd\b', m.group('TimeWindowEnd'), line)
    print(line.rstrip())

输出：

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

【讨论】：

【解决方案5】：

找到如下所示的明确解决方案：

import re

input_str = """
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
"""

# Divide input string into two parts: header, body
header = input_str.split('\n')[1]
body = '\n'.join(input_str.split('\n')[2:])

# Find elements to be replaced
ri = re.findall('\d{2}/\d{2}/\d{4}',header)
ri.extend(re.findall('\d{2}:\d{2}:\d{2}',header))

# Replace elements
new_header = header.replace(ri[0],'')\
                   .replace(ri[1],'')\
                   .replace(ri[2],'')

new_body = body.replace('Date',ri[0])\
               .replace('TimeWindowStart',ri[1])\
               .replace('TimeWindowEnd',ri[2])

# Construct the result string
full_string = new_header + '\n\n' + new_body

只需找到要替换为正则表达式的项目并执行普通字符串替换即可。我认为它是有效的，直到你只有很少的元素。

【讨论】：