Regular expression to match white space only when space found between only numeric values, and not find the space when comma found between two words

You may use

(?<=[A-Za-z\d])\s+(?=\d)|(?<=\d)\s+(?=[A-Za-z])

See the regex demo

Details

• (?<=[A-Za-z\d])\s+(?=\d) - one or more whitespace chars immediately preceded with an alphanumeric char and immediately followed with a digit
• | - or
• (?<=\d)\s+(?=[A-Za-z]) - one or more whitespace chars immediately preceded with a digit char and immediately followed with a letter.

Alternative regex:

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

Try it out at: https://regex101.com/