Remove characters other than alphanumeric from first 4 values of string Python

I need to remove characters other than alphanumeric from first 4 characters of string. I figured out how to do it for the whole string but not sure how to process only the first 4 values.

Data : '1/5AN 4/41 45'

Expected: '15AN 4/41 45'

Here is the code to remove the non-alphanumeric characters from string.

strValue = re.sub(r'[^A-Za-z0-9 ]+', '', strValue)

Any suggestions?

>Solution :

Using string slicing is one possibility:

import re

strValue = '1/5AN 4/41 45'
strValue = re.sub(r'[^A-Za-z0-9 ]+', '', strValue[:4]) + strValue[4:]

print(strValue)

Outputs: 15AN 4/41 45