由于我想将列表(url_key
)中字符串的每个元素作为正则表达式来标识另一个列表中的元素是否具有模式,因此我需要使用python为url_key
中每个元素的所有非单词字符添加反斜杠。你知道吗
我的代码示例:
import re
sentences = ["Disallow DCCP sockets due to such NFC-3456",
"Check at http://www.n.io/search?query=title++sub/file.html",
"Specifies the hash algorithm on them"]
url_key = ['www.n.io/search?query=title++sub', 'someweb.org/dirs.io'] # there are thousands of elements
add_key = ['NFC-[0-9]{4}', 'CEZ-[0-9a-z]{4,8}'] # there are hundreds of elements
pattern = url_key + add_key
mykey = re.compile('(?:% s)' % '|'.join(pattern))
for item in sentences:
if mykey.search(item):
print (item, ' --> Keyword is found')
else:
print (item, ' --> Keyword is not Found')
但是这个代码给了我一个错误:
error Traceback (most recent call last)
<ipython-input-80-5348ee9c65ec> in <module>()
8
9 pattern = url_key + add_key
---> 10 mykey = re.compile('(?:% s)' % '|'.join(pattern))
11
12 for item in sentences:
~/anaconda3/lib/python3.6/re.py in compile(pattern, flags)
231 def compile(pattern, flags=0):
232 "Compile a regular expression pattern, returning a pattern object."
--> 233 return _compile(pattern, flags)
234
235 def purge():
~/anaconda3/lib/python3.6/re.py in _compile(pattern, flags)
299 if not sre_compile.isstring(pattern):
300 raise TypeError("first argument must be string or compiled pattern")
--> 301 p = sre_compile.compile(pattern, flags)
302 if not (flags & DEBUG):
303 if len(_cache) >= _MAXCACHE:
~/anaconda3/lib/python3.6/sre_compile.py in compile(p, flags)
560 if isstring(p):
561 pattern = p
--> 562 p = sre_parse.parse(p, flags)
563 else:
564 pattern = None
~/anaconda3/lib/python3.6/sre_parse.py in parse(str, flags, pattern)
853
854 try:
--> 855 p = _parse_sub(source, pattern, flags & SRE_FLAG_VERBOSE, 0)
856 except Verbose:
857 # the VERBOSE flag was switched on inside the pattern. to be
~/anaconda3/lib/python3.6/sre_parse.py in _parse_sub(source, state, verbose, nested)
414 while True:
415 itemsappend(_parse(source, state, verbose, nested + 1,
--> 416 not nested and not items))
417 if not sourcematch("|"):
418 break
~/anaconda3/lib/python3.6/sre_parse.py in _parse(source, state, verbose, nested, first)
763 sub_verbose = ((verbose or (add_flags & SRE_FLAG_VERBOSE)) and
764 not (del_flags & SRE_FLAG_VERBOSE))
--> 765 p = _parse_sub(source, state, sub_verbose, nested + 1)
766 if not source.match(")"):
767 raise source.error("missing ), unterminated subpattern",
~/anaconda3/lib/python3.6/sre_parse.py in _parse_sub(source, state, verbose, nested)
414 while True:
415 itemsappend(_parse(source, state, verbose, nested + 1,
--> 416 not nested and not items))
417 if not sourcematch("|"):
418 break
~/anaconda3/lib/python3.6/sre_parse.py in _parse(source, state, verbose, nested, first)
617 if item[0][0] in _REPEATCODES:
618 raise source.error("multiple repeat",
--> 619 source.tell() - here + len(this))
620 if sourcematch("?"):
621 subpattern[-1] = (MIN_REPEAT, (min, max, item))
error: multiple repeat at position 31
预期结果:
Disallow DCCP sockets due to such NFC-3456 --> Keyword is found
Check at http://www.n.io/search?query=title++sub/file.html --> Keyword is found
Specifies the hash algorithm on them --> Keyword is not found
任何帮助都将不胜感激。谢谢。你知道吗
您的主要问题是字符串转义在regex替换转义之前生效。切换到原始字符串(禁止字符串转义)并转义反斜杠(因为
\\
本身就是一个替换转义)将解决此问题:请注意,您可能不需要如此广泛的转义。如果您只想转义regex特殊字符,
re.escape
将为您执行以下操作:不添加不必要的转义符(那些不需要取消正则表达式字符专用化的转义符)。你知道吗
您应该使用原始字符串:
或者也要避开反斜杠:
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