Python RegEx删除新行（不应存在）

Question

I got some text extracted and wish to clean it up by RegEx.

I have learned basic RegEx but not sure how to build this one:

str = '''
this is 
a line that has been cut.
This is a line that should start on a new line
'''

should be converted to this:

str = '''
this is a line that has been cut.
This is a line that should start on a new line
'''

This r'\\w\\n\\w' seems to catch it, but not sure how to replace the new line with space and not touch the end and beginning of words

Answer 1

You can use this lookbehind regex for re.sub :

>>> str = '''
... this is
... a line that has been cut.
... This is a line that should start on a new line
... '''
>>> print re.sub(r'(?<!\.)\n', '', str)
this is a line that has been cut.
This is a line that should start on a new line
>>>

RegEx Demo

(?<!\\.)\\n matches all line breaks that are not preceded by a dot.

If you don't want a match based on presence of dot then use:

re.sub(r'(?<=\w\s)\n', '', str)

RegEx Demo 2