Hi John,
After a bit of thinking:
# fill in the appropriate path and pattern
filenames<-list.files(path=???,pattern=???)
for(filename in filenames) {
filefirst<-sapply(strsplit(filename,"[.]"),"[",1)
# delete all non-digits
fileno<-gsub("[^[:digit:]]","",filefirst)
file.rename(filename,paste("01Gen",fileno,".mp3",sep=""))
}
Jim