Question

我正在尝试删除与新闻来源列表中排除的来源列表匹配的特定URL。我只想打印与我的正则表达式不匹配的URL。我也只想将列表news_articles中的项目打印一次。

如何仅打印不匹配的URL？

如何只将不匹配的URL打印一次？

import re

sources_to_exclude = ['cnn.com','france24.com','reuters.com']

news_articles = ['http://www.chicagotribune.com/news/nationworld/ct-south-africa-trump-tweet-20180823-story.html',
         'https://www.theatlantic.com/international/archive/2018/08/trump-rule-of-law-south-africa-farmers/568390',
         'https://www.aljazeera.com/news/2018/08/south-africa-calls-trump-misinformed-land-policy-180823060142595.html',
         'https://www.timeslive.co.za/politics/2018-08-23-trumps-administration-to-monitor-land-expropriation-in-south-africa',
         'https://mg.co.za/article/2018-08-23-south-african-politicians-resist-trumps-falsehoods-about-south-africa',
         'https://www.cnn.com/2018/08/22/africa/south-africa-racist-rant-video/index.html',
         'https://www.reuters.com/article/us-safrica-usa-presidency/south-africa-to-seek-clarification-from-us-embassy-on-trumps-land-reform-tweet-sabc-idUSKCN1L80JI',
         'https://www.thedailybeast.com/trump-bemoans-persecuted-white-farmers-in-south-africa',
         'https://www.france24.com/en/20180823-south-africa-recall-mostert-second-argentina-test']

for result in news_articles:
  for link in sources_to_exclude:
    regex = '((http[s]?|ftp):\/)?\/?([^:\/\s]+)?({})\/([^\/]+)'.format(link)
    match = re.search(r'{}'.format(regex), result, re.IGNORECASE)
    if match:
      print ('Matched regex:  {}'.format(result))
    else:
      # I only want to print items that DID NOT match the regex pattern
      # I also want to print these items once.
      print('Did not matched regex:  {}'.format(result))

Answer 1

您可以使用列表理解：

[i for i in news_articles if not re.search('|'.join(sources_to_exclude),i)]

Out[610]: 
['http://www.chicagotribune.com/news/nationworld/ct-south-africa-trump-tweet-20180823-story.html',
 'https://www.theatlantic.com/international/archive/2018/08/trump-rule-of-law-south-africa-farmers/568390',
 'https://www.aljazeera.com/news/2018/08/south-africa-calls-trump-misinformed-land-policy-180823060142595.html',
 'https://www.timeslive.co.za/politics/2018-08-23-trumps-administration-to-monitor-land-expropriation-in-south-africa',
 'https://mg.co.za/article/2018-08-23-south-african-politicians-resist-trumps-falsehoods-about-south-africa',
 'https://www.thedailybeast.com/trump-bemoans-persecuted-white-farmers-in-south-africa']

您也可以这样做：

re.sub('^.*('+'|'.join(sources_to_exclude)+').*$', "", "\n".join(news_articles),flags=re.M).split()
Out[612]: 
['http://www.chicagotribune.com/news/nationworld/ct-south-africa-trump-tweet-20180823-story.html',
 'https://www.theatlantic.com/international/archive/2018/08/trump-rule-of-law-south-africa-farmers/568390',
 'https://www.aljazeera.com/news/2018/08/south-africa-calls-trump-misinformed-land-policy-180823060142595.html',
 'https://www.timeslive.co.za/politics/2018-08-23-trumps-administration-to-monitor-land-expropriation-in-south-africa',
 'https://mg.co.za/article/2018-08-23-south-african-politicians-resist-trumps-falsehoods-about-south-africa',
 'https://www.thedailybeast.com/trump-bemoans-persecuted-white-farmers-in-south-africa']

Answer 2

您的代码即将完成。这应该起作用：

for result in news_articles:
    for link in sources_to_exclude:
        regex = '((http[s]?|ftp):\/)?\/?([^:\/\s]+)?({})\/([^\/]+)'.format(link)
        match = re.search(r'{}'.format(regex), result, re.IGNORECASE)
        if match is not None:
            break
    else:
        print('Did not match any regex: {}'.format(result))

Python在else循环上支持for。如果循环正常存在（未使用break停止循环），则执行else块。当循环中断时，如果有任何正则表达式匹配，则仅在没有正则表达式匹配时才执行（并打印链接）。

仅打印不匹配的正则表达式

2 个答案: