Python：在字符串中查找模式
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Python: Find pattern in a string
提问by user3480774
I am trying to find a way to match a pattern p in a string s in python.
我试图找到一种方法来匹配 python 中字符串 s 中的模式 p。
s = 'abccba'
ss = 'facebookgooglemsmsgooglefacebook'
p = 'xyzzyx'
# s, p -> a, z # s and p can only be 'a' through 'z'
def match(s, p):
if s matches p:
return True
else:
return False
match(s, p) # return True
match(ss, p) # return True
I just tried:
我刚试过：
import re
s = "abccba"
f = "facebookgooglemsmsgooglefacebook"
p = "xyzzyx"
def fmatch(s, p):
p = re.compile(p)
m = p.match(s)
if m:
return True
else:
return False
print fmatch(s, p)
print fmatch(f, p)
Both return false; they are supposed to be true.
两者都返回false；他们应该是真的。
采纳答案by Stefan Pochmann
I convert your pattern into a regular expression that can then be used by re.match. For example, your xyzzyxbecomes (.+)(.+)(.+)\3\2\1$(the first occurrence of each letter becomes a capture group (.+), and subsequent occurences become the proper back reference).
我将您的模式转换为正则表达式，然后可以由re.match. 例如，您的xyzzyx变成(.+)(.+)(.+)\3\2\1$（每个字母的第一次出现成为一个捕获组(.+)，随后出现的成为正确的反向引用）。
import re
s = 'abccba'
ss = 'facebookgooglemsmsgooglefacebook'
p = 'xyzzyx'
def match(s, p):
nr = {}
regex = []
for c in p:
if c not in nr:
regex.append('(.+)')
nr[c] = len(nr) + 1
else:
regex.append('\%d' % nr[c])
return bool(re.match(''.join(regex) + '$', s))
print(match(s, p))
print(match(ss, p))
回答by manglano
Compile a Python regular expressions object for some pattern of interest and then pass the string to its Match(string) method. You'll want to use a matchobject if you need a boolean output: https://docs.python.org/3/library/re.html#match-objects
为某些感兴趣的模式编译 Python 正则表达式对象，然后将字符串传递给它的 Match(string) 方法。match如果您需要布尔输出，则需要使用对象：https: //docs.python.org/3/library/re.html#match-objects
Example: Check string s for any word character (that is, alphanumerics)
示例：检查字符串 s 中是否有任何单词字符（即字母数字）
def match_string(s):
##compile a regex for word characters
regex = re.compile("\w")
##return the result of the match function on string
return re.match(s)
Hope it helps!
希望能帮助到你！
回答by Tenzin
You could make use of regular expressions.
Have a look here for some examples: Link
您可以使用正则表达式。
看看这里的一些例子：链接
I think you could use re.search()
我想你可以用 re.search()
Ecample:
营地：
import re
stringA = 'dog cat mouse'
stringB = 'cat'
# Look if stringB is in stringA
match = re.search(stringB, stringA)
if match:
print('Yes!')
回答by jatal
If I'm understanding your question, you're looking for a pythonic approach to pattern matching across a set of strings.
如果我理解你的问题，你正在寻找一种 pythonic 方法来跨一组字符串进行模式匹配。
Here is an example demonstrating the use of list comprehensions to achieve this goal.
这是一个示例，演示了使用列表理解来实现此目标。
I hope it helps you reach your goal. Please let me know if I can help further. - JL
我希望它能帮助你达到你的目标。如果我能提供进一步帮助，请告诉我。- JL
Demonstrate No Match Found
证明未找到匹配项
>>> import re
>>> s = ["abccba", "facebookgooglemsmsgooglefacebook"]
>>> p = "xyzzyx"
>>> result = [ re.search(p,str) for str in s ]
>>> result
[None, None]
Demonstrate Combination of Matches and No Match in the result
在结果中展示匹配和不匹配的组合
>>> p = "abc"
>>> result = [ re.search(p,str) for str in s ]
>>> result
[<_sre.SRE_Match object at 0x100470780>, None]
>>> [ m.group(0) if m is not None else 'No Match' for m in result ]
['abc', 'No Match']
>>> [ m.string if m is not None else 'No Match' for m in result ]
['abccba', 'No Match']
Demonstrate single statement
演示单条语句
>>> [ m.string if m is not None else 'No Match' for m in [re.search(p,str) for str in s] ]
['abccba', 'No Match']
