python - 使用 python re 转换字符串

Question

我得到一条字符串:

>>> line = "  abc\n  def\n\n  ghi\n  jkl"
>>> print line
  abc
  def

  ghi
  jkl

我想将其转换为“abcdef\n\n ghijkl”，例如:

>>> print "  abcdef\n\n  ghijkl"
  abcdef

  ghijkl

我尝试了 python re 模块，并写了这样的内容:

re.sub('(?P<word1>[^\n\s])\n\s*(?P<word2>[^\n\s])', '\g<word1>\g<word2>', line)

但我明白了:

>>> re.sub('(?P<word1>[^\n\s])\n\s*(?P<word2>[^\n\s])', '\g<word1>\g<word2>', line)
Out: '  abcdefghijkl'

在我看来，\n\s*部分也匹配\n\n。谁能指出我哪里错了？

Answer 1

\s 匹配空格、\t、\n(以及，具体取决于您的正则表达式引擎)一些其他空白字符。

所以如果你只想替换单个换行符+空格/制表符，你可以使用这个:

newline = re.sub(r"(?<!\n)\n[ \t]*(?!\n)", "", line)

说明:

(?<!\n) # Assert that the previous character isn't a newline
\n      # Match a newline
[ \t]*  # Match any number of spaces/tabs
(?!\n)  # Assert that the next character isn't a newline

在Python中:

>>> line = "  abc\n  def\n\n  ghi\n  jkl"
>>> newline = re.sub(r"(?<!\n)\n[ \t]*(?!\n)", "", line)
>>> print newline
  abcdef

  ghijkl