Question

XML specification列出了一堆非法或“气馁”的Unicode字符。给定一个字符串，如何从中删除所有非法字符？

我提出了以下正则表达式，但它有点满口。

illegal_xml_re = re.compile(u'[\x00-\x08\x0b-\x1f\x7f-\x84\x86-\x9f\ud800-\udfff\ufdd0-\ufddf\ufffe-\uffff]')
clean = illegal_xml_re.sub('', dirty)

（Python 2.5不知道0xFFFF以上的Unicode字符，所以不需要过滤那些。）

Answer 1

最近我们（Trac XmlRpcPlugin维护者）已经被告知上面的正则表达式剥离了Python窄版本上的代理对（参见th:comment:13:ticket:11050）。另一种方法是使用以下正则表达式（参见th:changeset:13729）。

_illegal_unichrs = [(0x00, 0x08), (0x0B, 0x0C), (0x0E, 0x1F), 
                        (0x7F, 0x84), (0x86, 0x9F), 
                        (0xFDD0, 0xFDDF), (0xFFFE, 0xFFFF)] 
if sys.maxunicode >= 0x10000:  # not narrow build 
        _illegal_unichrs.extend([(0x1FFFE, 0x1FFFF), (0x2FFFE, 0x2FFFF), 
                                 (0x3FFFE, 0x3FFFF), (0x4FFFE, 0x4FFFF), 
                                 (0x5FFFE, 0x5FFFF), (0x6FFFE, 0x6FFFF), 
                                 (0x7FFFE, 0x7FFFF), (0x8FFFE, 0x8FFFF), 
                                 (0x9FFFE, 0x9FFFF), (0xAFFFE, 0xAFFFF), 
                                 (0xBFFFE, 0xBFFFF), (0xCFFFE, 0xCFFFF), 
                                 (0xDFFFE, 0xDFFFF), (0xEFFFE, 0xEFFFF), 
                                 (0xFFFFE, 0xFFFFF), (0x10FFFE, 0x10FFFF)]) 

_illegal_ranges = ["%s-%s" % (unichr(low), unichr(high)) 
                   for (low, high) in _illegal_unichrs] 
_illegal_xml_chars_RE = re.compile(u'[%s]' % u''.join(_illegal_ranges))

P.S。请参阅this post on surrogates解释它们的用途。

更新，以便不匹配（替换）0x0D {{1}}。

Answer 2

您还可以使用unicode的translate方法删除选定的代码点。但是，您拥有的映射相当大（2128个代码点），这可能比使用正则表达式慢得多：

ranges = [(0, 8), (0xb, 0x1f), (0x7f, 0x84), (0x86, 0x9f), (0xd800, 0xdfff), (0xfdd0, 0xfddf), (0xfffe, 0xffff)]
# fromkeys creates  the wanted (codepoint -> None) mapping
nukemap = dict.fromkeys(r for start, end in ranges for r in range(start, end+1))
clean = dirty.translate(nukemap)

Answer 3

这是Olemis Lang针对Python 3的答案的更新版本。

import re
import sys

illegal_unichrs = [(0x00, 0x08), (0x0B, 0x0C), (0x0E, 0x1F),
                   (0x7F, 0x84), (0x86, 0x9F),
                   (0xFDD0, 0xFDDF), (0xFFFE, 0xFFFF)]
if sys.maxunicode >= 0x10000:  # not narrow build
    illegal_unichrs.extend([(0x1FFFE, 0x1FFFF), (0x2FFFE, 0x2FFFF),
                            (0x3FFFE, 0x3FFFF), (0x4FFFE, 0x4FFFF),
                            (0x5FFFE, 0x5FFFF), (0x6FFFE, 0x6FFFF),
                            (0x7FFFE, 0x7FFFF), (0x8FFFE, 0x8FFFF),
                            (0x9FFFE, 0x9FFFF), (0xAFFFE, 0xAFFFF),
                            (0xBFFFE, 0xBFFFF), (0xCFFFE, 0xCFFFF),
                            (0xDFFFE, 0xDFFFF), (0xEFFFE, 0xEFFFF),
                            (0xFFFFE, 0xFFFFF), (0x10FFFE, 0x10FFFF)])

illegal_ranges = [fr'{chr(low)}-{chr(high)}' for (low, high) in illegal_unichrs]
xml_illegal_character_regex = '[' + ''.join(illegal_ranges) + ']'
illegal_xml_chars_re = re.compile(xml_illegal_character_regex)
# filtered_string = illegal_xml_chars_re.sub('', original_string)

在python中过滤非法xml unicode字符的快速方法？

3 个答案: