正则表达式和特殊字符本身

Question

I want to replace the character & with and , but only when & is by itself. I try the following in Python 2.7.3 :

import re
re.sub('&', 'and', '& r&b')

I get and randb , but what I want is and r&b .

re.sub('\b&\b', 'and', '& r&b')

Doesn't work either. Any suggestions? Also, what's the expression if I just wanted a unique combination of normal characters and special characters, like if I want a&b , but not a&bc ?

Couldn't find the answer in similar questions, so thanks in advance!

Answer 1

Not knowing what "by itself" means. Btw, nobody knows what that means in regex.

Ror your specific example,

search (^| )&( |$)
replace $1and$2

Don't know Python though.

Edit: In Python

import re
re.sub('(^| )&( |$)', r'\1and\2', '& r&b')

Answer 2

& is treated as a non word character. So just use this simple substitution.

Note: this will work for most usual cases in normal text.

>>> re.sub(r" & ", " and ", " & r&b")
' and r&b'