Keep duplicates in a list in Python

Question

I know this is probably an easy answer but I can\'t figure it out. What is the best way in Python to keep the duplicates in a list:

x = [1,2,2,2,3,4,5,6,6,7         


        

Answer 1

This is a short way to do it if the list is sorted already:

x = [1,2,2,2,3,4,5,6,6,7]

from itertools import groupby
print [key for key,group in groupby(x) if len(list(group)) > 1]