当且仅当前一个字母也不也是大写的Pythonic方式才能在大写字母前添加空间

Question

As the title says, I would like to add spaces before capital letters, but only if the prior letter is not also a capital letter. So 'HelloCHARLIE this isBob.' should become 'Hello CHARLIE this is Bob.'

Answer 1

(?<![A-Z])(?<!^)([A-Z])

print re.sub(r"(?<![A-Z])(?<!^)([A-Z])",r" \1",x)

This works.See demo.Use a negative lookbehind to ensure preceding character is not Capital or start of string.

See demo.

http://regex101.com/r/cH8vN2/1

Answer 2

One solution would be

import re
string = 'HelloCHARLIE this isBob.'
re.sub(r'(?<=[a-z])(?=[A-Z])', ' ', string)

prints

'Hello CHARLIE this is Bob.'