How To Insert Space Between Alphabet Characters And Numeric Character Using Regex?

I'm trying to insert space between numeric characters and alphabet character so I can convert numeric character to words like : Input : subject101 street45 Output :

Solution 1:

Try this Regex:

(?i)(?<=\d)(?=[a-z])|(?<=[a-z])(?=\d)

Click for Demo

Replace each match with a space

Explanation:

• (?i) - modifier to make the matches case-insensitive
• (?<=\d)(?=[a-z]) - finds the position just preceded by a digit and followed by a letter
• | - OR
• (?<=[a-z])(?=\d) - finds the position just preceded by a letter and followed by a digit

Code output

import re
regex = r"(?i)(?<=\d)(?=[a-z])|(?<=[a-z])(?=\d)"
test_str = ("subject101\n""     street45")
subst = " "
result = re.sub(regex, subst, test_str, 0)
if result:
    print (result)

Solution 2:

You can use if statement (?(#group)) in regex to check if char is digit or a letter.

Regex: (?<=([a-z])|\d)(?=(?(1)\d|[a-z]))

Python code:

defaddSpace(text):
    return re.sub(r'(?<=([a-z])|\d)(?=(?(1)\d|[a-z]))', ' ', text)

Output:

addSpace('subject101')
>>> subject 101
addSpace('101subject')
>>> 101 subject

Solution 3:

A way to do this would be to pass a callable to re.sub. This allows you to reuse the matched substring to generate the replacement value.

subject = '101subject101'

s = re.sub(r'[a-zA-Z]\d|\d[a-zA-Z]', lambda m: ' '.join(m.group()), subject )
# s: '101 subject 101'