good.append(x) if x in goodvals else bad.append(x)This elegant and concise answer by @dansalmo showed up buried in the comments, so I'm just reposting it here as an answer so it can get the prominence it deserves, especially for new readers.
Complete example:
good, bad = [], []for x in my_list: good.append(x) if x in goodvals else bad.append(x)