第一种:
L1 = [5, 4, 5, 3, 2, 4, 3, 2, 7, 7]
L2 = []
for i in L1:
if i not in L2:
L2.append(i)
>>> print L2
[5, 4, 3, 2, 7]
第二种:
L1 = ['c', 'd', 'r', 'd', 'r' ,'a', 'C']
L2 = list(set(L1))
L2.sort(key=L1.index)
注:第二种方法来自
http://blog.youkuaiyun.com/shuifa2008/article/details/38085955