正则表达式:如何匹配字符串末尾的键值对序列 [英] Regex: How to match sequence of key-value pairs at end of string
问题描述
我正在尝试匹配出现在(长)字符串末尾的键值对.字符串看起来像(我替换为"\ n")
I am trying to match key-value pairs that appear at the end of (long) strings. The strings look like (I replaced the "\n")
my_str = "lots of blah
key1: val1-words
key2: val2-words
key3: val3-words"
所以我希望匹配"key1:val1字"，"key2:val2字"和"key3:val3字".
so I expect matches "key1: val1-words", "key2: val2-words" and "key3: val3-words".
- 一组可能的键名是已知的.
- 并非所有可能的键都出现在每个字符串中.
- 每个字符串中至少出现两个键(如果这样更容易匹配).
- val-word可以是几个单词.
- 键值对仅应在字符串末尾进行匹配.
- 我正在使用Python re模块.
我在想
re.compile('(?:tag1|tag2|tag3):')
加上一些前瞻性断言的东西将是一个解决方案.不过我做不到.我该怎么办?
plus some look-ahead assertion stuff would be a solution. I can't get it right though. How do I do?
谢谢.
/大卫
实际示例字符串:
my_str = u'ucourt métrage pour kino session volume 18\nThème: O sombres héros\nContraintes: sous titrés\nAuthor: nicoalabdou\nTags: wakatanka productions court métrage kino session humour cantat bertrand noir désir sombres héros mer medine marie trintignant femme droit des femmes nicoalabdou pute soumise\nPosted: 06 June 2009\nRating: 1.3\nVotes: 3'
基于Mikel的解决方案，我现在使用以下内容:
Based on Mikel's solution I am now using the following:
my_tags = ['\S+'] # gets all tags
my_tags = ['Tags','Author','Posted'] # selected tags
regex = re.compile(r'''
\n # all key-value pairs are on separate lines
( # start group to return
(?:{0}): # placeholder for tags to detect '\S+' == all
\s # the space between ':' and value
.* # the value
) # end group to return
'''.format('|'.join(my_tags)), re.VERBOSE)regex.sub('',my_str) # return my_str without matching key-vaue lines regex.findall(my_str) # return matched key-value lines
regex.sub('',my_str) # return my_str without matching key-vaue lines regex.findall(my_str) # return matched key-value lines
推荐答案
负零宽度超前为(?!pattern).
在 re模块文档页面中部分提及.
(?!...)
如果...下一个不匹配，则进行匹配.这是一个否定的超前断言.例如，仅当Isaac(?！Asimov)后面不带"Asimov"时，它才会与"Isaac"匹配.
Matches if ... doesn’t match next. This is a negative lookahead assertion. For example, Isaac (?!Asimov) will match 'Isaac ' only if it’s not followed by 'Asimov'.
因此，您可以使用它来匹配某个键后的任意数量的单词，但不能使用(?!\S+:)\S+之类的键来匹配该键.
So you could use it to match any number of words after a key, but not a key using something like (?!\S+:)\S+.
完整的代码如下:
regex = re.compile(r'''
[\S]+: # a key (any word followed by a colon)
(?:
\s # then a space in between
(?!\S+:)\S+ # then a value (any word not followed by a colon)
)+ # match multiple values if present
''', re.VERBOSE)
matches = regex.findall(my_str)
哪个给
['key1: val1-words ', 'key2: val2-words ', 'key3: val3-words']
如果您使用以下命令打印键/值:
If you print the key/values using:
for match in matches:
print match
它将打印:
key1: val1-words
key2: val2-words
key3: val3-words
或者使用更新后的示例，它将打印:
Or using your updated example, it would print:
Thème: O sombres héros
Contraintes: sous titrés
Author: nicoalabdou
Tags: wakatanka productions court métrage kino session humour cantat bertrand noir désir sombres héros mer medine marie trintignant femme droit des femmes nicoalabdou pute soumise
Posted: 06 June 2009
Rating: 1.3
Votes: 3
您可以使用以下方法将每个键/值对转换成字典:
You could turn each key/value pair into a dictionary using something like this:
pairs = dict([match.split(':', 1) for match in matches])
这将使查找所需的键(和值)更加容易.
which would make it easier to look up only the keys (and values) you want.
更多信息:
- Python re module documentation
- Python Regular Expression HOWTO
- Perl Regular Expression Reference "perlreref"
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