R regex gsub separate letters and numbers

Question

I have a string that\'s mixed letters and numbers:

\"The sample is 22mg\"

I\'d like to split strings where a number is immediately followed by

Answer 1

You need to use capturing parentheses in the regular expression and group references in the replacement. For example:

gsub('([0-9])([[:alpha:]])', '\\1 \\2', 'This is a test 22mg')

There's nothing R-specific here; the R help for regex and gsub should be of some use.