Hi, If I have a string of consecutive chars followed by consecutive numbers and then chars, like "absdfds0213451ab", how to separate the consecutive chars from consecutive numbers? grep doesn't seem to be helpful grep("[a-z]","absdfds0213451ab", ignore.case=T) [1] 1 grep("[0-9]","absdfds0213451ab", ignore.case=T) [1] 1 Thanks Carol [[alternative HTML version deleted]]