Python RegEx跳过前几个字符？
[英]Python RegEx skipping the first few characters?
问题描述
Hey I have a fairly basic question about regular expressions. 
嘿，我对正则表达式有一个相当基本的问题。 I want to just return the text inside (and including) the body tags, and I know the following isn't right because it'll also match all the characters before the opening body tag. 我只想返回正文标签中（包括正文）的文字，并且我知道以下内容不正确，因为它还会匹配正文标签前的所有字符。 I was wondering how you would go about skipping those? 我想知道您将如何跳过这些？
x = re.match('(.*<body).*?(</body>)', fileString)
Thanks! 谢谢！
6 个解决方案
解决方案1
9 2009-10-25 13:32:09
I don't know Python, but here's a quick example thrown together using Beautiful Soup , which I often see recommended for Python HTML parsing. 我不了解Python，但这是一个使用Beautiful Soup的简单示例，我经常看到推荐将其用于Python HTML解析。
import BeautifulSoup
soup = BeautifulSoup(fileString)
bodyTag = soup.html.body.string
That will (in theory) deal with all the complexities of HTML, which is very difficult with pure regex-based answers, because it's not what regex was designed for. 从理论上讲，这将处理HTML的所有复杂性，这对于基于纯正则表达式的答案非常困难，因为这不是正则表达式的目的。
解决方案2
2 已采纳 2009-10-25 13:18:43
Here is some example code which uses regex to find all the text between <body>...</body> tags. 这是一些使用正则表达式查找<body>...</body>标记之间的所有文本的示例代码。 Although this demonstrates some features of python's re module, note that the Beautiful Soup module is very easy to use and is a better tool to use if you plan on parsing HTML or XML. 尽管这展示了python re模块的某些功能，但请注意， Beautiful Soup模块非常易于使用，如果计划解析HTML或XML，则它是更好的工具。 (See below for an example of how you could parse this using BeautifulSoup.) （有关如何使用BeautifulSoup解析此示例的示例，请参见下文。）
#!/usr/bin/env python
import re
# Here we have a string with a multiline <body>...</body>
fileString='''baz<body>foo
baby foo
baby foo
baby foo
</body><body>bar</body>'''
# re.DOTALL tells re that '.' should match any character, including newlines.
x = re.search('(<body>.*?</body>)', fileString, re.DOTALL)
for match in x.groups():
print(match)
# <body>foo
# baby foo
# baby foo
# baby foo
# </body>
If you wish to collect all matches, you could use re.findall: 如果您希望收集所有匹配项，则可以使用re.findall：
print(re.findall('(<body>.*?</body>)', fileString, re.DOTALL))
# ['<body>foo\nbaby foo\nbaby foo\nbaby foo\n</body>', '<body>bar</body>']
and if you plan to use this pattern more than once, you can pre-compile it: 如果您打算多次使用此模式，则可以对其进行预编译：
pat=re.compile('(<body>.*?</body>)', re.DOTALL)
print(pat.findall(fileString))
# ['<body>foo\nbaby foo\nbaby foo\nbaby foo\n</body>', '<body>bar</body>']
And here is how you could do it with BeautifulSoup: 这是使用BeautifulSoup的方法：
#!/usr/bin/env python
from BeautifulSoup import BeautifulSoup
fileString='''baz<body>foo
baby foo
baby foo
baby foo
</body><body>bar</body>'''
soup = BeautifulSoup(fileString)
print(soup.body)
# <body>foo
# baby foo
# baby foo
# baby foo
# </body>
print(soup.findAll('body'))
# [<body>foo
# baby foo
# baby foo
# baby foo
# </body>, <body>bar</body>]
解决方案3
0 2009-10-25 15:50:23
You cannot parse HTML with regex. 您无法使用正则表达式解析HTML。 HTML is not a regular language. HTML不是常规语言。 Use an HTML parser like lxml instead. 使用类似lxml的HTML解析器。
解决方案4
-1 2009-10-25 13:18:22
x = re.match('.*(<body>.*?</body>)', fileString)
考虑最小化HTML解析。
解决方案5
-1 2009-10-25 13:25:40
x = re.search('(<body>.*</body>)', fileString)
x.group(1)
Less typing than the match answers 打字比比赛答案少
解决方案6
-1 2009-10-25 13:41:02
Does your fileString contain multiple lines ? 您的fileString是否包含多行 ？ In that case you may need to specify it or skip the lines explicitly: 在这种情况下，您可能需要指定它或显式跳过以下行：
x = re.match(r"(?:.|\n)*(<body>(?:.|\n)*</body>)", fileString)
or, more simply with the re module: 或者，更简单地说，使用re模块：
x = re.match(r".*(<body>.*</body>)", fileString, re.DOTALL)
x.groups()[0] should contain your string if x is not None. 如果x不为None，则x.groups()[0]应包含您的字符串。
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