在python中获取2个字符之间的字符串
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getting string between 2 characters in python
提问by bellere
I need to get certain words out from a string in to a new format. For example, I call the function with the input:
我需要将字符串中的某些单词转换为新格式。例如，我使用输入调用函数：
text2function('$sin (x)$ is an function of x')
and I need to put them into a StringFunction:
我需要将它们放入一个 StringFunction 中：
StringFunction(function, independent_variables=[vari])
where I need to get just 'sin (x)' for function and 'x' for vari. So it would look like this finally:
我只需要为函数获取 'sin (x)'，而为 vari 获取'x'。所以它最终看起来像这样：
StringFunction('sin (x)', independent_variables=['x']
problem is, I can't seem to obtain function and vari. I have tried:
问题是，我似乎无法获得函数和变量。我试过了：
start = string.index(start_marker) + len(start_marker)
end = string.index(end_marker, start)
return string[start:end]
and
和
r = re.compile('$()$')
m = r.search(string)
if m:
lyrics = m.group(1)
and
和
send = re.findall('$([^"]*)$',string)
all seems to seems to give me nothing. Am I doing something wrong? All help is appreciated. Thanks.
一切似乎都没有给我什么。难道我做错了什么？感谢所有帮助。谢谢。
回答by Blender
$is a special character in regex (it denotes the end of the string). You need to escape it:
$是正则表达式中的一个特殊字符（它表示字符串的结尾）。你需要逃避它：
>>> re.findall(r'$(.*?)$', '$sin (x)$ is an function of x')
['sin (x)']
回答by Martijn Pieters
You need to start searching for the second character beyondstart:
您需要开始搜索超出的第二个字符start：
end = string.index(end_marker, start + 1)
because otherwise it'll find the same character at the same location again:
因为否则它会再次在同一位置找到相同的字符：
>>> start_marker = end_marker = '$'
>>> string = '$sin (x)$ is an function of x'
>>> start = string.index(start_marker) + len(start_marker)
>>> end = string.index(end_marker, start + 1)
>>> string[start:end]
'sin (x)'
For your regular expressions, the $character is interpreted as an anchor, not the literal character. Escape it to match the literal $(and look for things that are not$instead of not ":
对于您的正则表达式，该$字符被解释为锚点，而不是文字字符。转义它以匹配文字$（并寻找不是$而不是不是的东西"：
send = re.findall('$([^$]*)$', string)
which gives:
这使：
>>> import re
>>> re.findall('$([^$]*)$', string)
['sin (x)']
The regular expression $()$otherwise doesn't really match anything between the parenthesis even if you did escape the $characters.
$()$否则，即使您确实对$字符进行了转义，正则表达式也不会真正匹配括号之间的任何内容。
回答by Soorej P
Tweeky way!
周到的方式！
>>> char1 = '('
>>> char2 = ')'
>>> mystr = "mystring(123234sample)"
>>> print mystr[mystr.find(char1)+1 : mystr.find(char2)]
123234sample
回答by Raja Govindan
If you want to cut a string between two identical characters (i.e, !234567890!) you can use
如果你想在两个相同的字符（即 !234567890！）之间剪切一个字符串，你可以使用
line_word = line.split('!')
print (line_word[1])
