如何比较python中的Rpm版本

I'm trying to find out how I can compare 2 lists of RPMS (Currently installed) and (Available in local repository) and see which RPMS are out of date. I've been tinkering with regex but there are so many different naming standards for RPMS that i can't get a good list to work with. I don't have the actual RPMS on my drive so i can't do rpm -qif.I'm trying to find out how I can compare 2 list