Python中的正则表达式和替换答案

【问题标题】：Regular expression and substitution in PythonPython中的正则表达式和替换
【发布时间】：2020-07-05 06:25:42
【问题描述】：

我有一个内容字符串，例如：

content =
"""
the patient monitoring system shall perform a daily device check from 1:30 am to 4:30 am (patient local time). if a device malfunction is detected, the daily device check shall send the malfunction to the clinician. if a patient health alarm is detected, the daily device check shall turn into full interrogation as specified in srs-3003. if no device or patient health issue identified, the daily device check shall end without further notification to the clinicians or patient. if a scheduled interrogation happens on the same day, the daily device check shall be skipped. if any device issue detected during the daily device check, the patient monitoring system shall alarm the patient with red urgent light. . if any patient health issue detected during the daily device check, the patient monitoring system shall alarm the patient with yellow warning light. . if a daily device check fails, it should be retried in 15 minutes up to 3 times. if a daily device check still fails after 3 times, the patient monitoring system shall end the interrogation and notify patient of the failed device check at 8 am that morning. there are 3 types of interrogations as below:
1. scheduled interrogation.
2. daily device check
3. patient initiated interrogation. an interrogation could fail due to the following reasons:
1. failed to establish communication.
2. communication lost.
3. failed to obtain a key data from the implanted device.
"""

并且我想替换像 1. 2. 3. 这样的副标题，但不想像 srs-3003 这样影响实际的内容编号。

如果我使用以下正则表达式： re.findall("\d{1}\.", content) 结果是['3.', '1.', '2.', '3.', '1.', '2.', '3.'] 和“3”。在 srs-3003. 中的内容将在下一步中被替换：

num_dot = re.findall("\d+\.", content)
for num in num_dot:
    content = content.replace(num, "")

我该如何继续？

【问题讨论】：

你需要re.sub("\d+\.","", content) re.sub 而不是re.findall

标签： python regex replace

【解决方案1】：

您的正则表达式符合要求。只是为了不匹配3. 中的srs-3003.，您可以添加^ 锚。比如：

^\d+\.

上述正则表达式的解释：

^ - 表示行首。
\d+ - 表示出现一次或多次的数字类。
\. - 从字面上匹配 .。 如果您还想删除每个编号点线前面的空间；请使用 + 或\s+。

你可以在here.找到上述正则表达式的demo

Python 中的示例实现：

import re

regex = r"^\d+\."

test_str = ("the patient monitoring system shall perform a daily device check from 1:30 am to 4:30 am (patient local time). if a device malfunction is detected, the daily device check shall send the malfunction to the clinician. if a patient health alarm is detected, the daily device check shall turn into full interrogation as specified in srs-3003. if no device or patient health issue identified, the daily device check shall end without further notification to the clinicians or patient. if a scheduled interrogation happens on the same day, the daily device check shall be skipped. if any device issue detected during the daily device check, the patient monitoring system shall alarm the patient with red urgent light. . if any patient health issue detected during the daily device check, the patient monitoring system shall alarm the patient with yellow warning light. . if a daily device check fails, it should be retried in 15 minutes up to 3 times. if a daily device check still fails after 3 times, the patient monitoring system shall end the interrogation and notify patient of the failed device check at 8 am that morning. there are 3 types of interrogations as below:\n"
    "1. scheduled interrogation.\n"
    "2. daily device check\n"
    "3. patient initiated interrogation. an interrogation could fail due to the following reasons:\n"
    "1. failed to establish communication.\n"
    "2. communication lost.\n"
    "3. failed to obtain a key data from the implanted device.")

subst = ""

# You can manually specify the number of replacements by changing the 4th argument
result = re.sub(regex, subst, test_str, 0, re.MULTILINE)

if result:
    print (result)

请在here.中找到上述程序的示例运行

【讨论】：