1 l1 = [‘a‘,1,‘c‘,‘b‘,2,‘b‘,‘c‘,‘d‘,‘a‘]
2 l2= sorted(set(l1),key=l1.index)
3 print(‘l2:‘,l2)
4 print(‘l1:‘,l1)
5 
6 #输出
7 #l2: [‘a‘, 1, ‘c‘, ‘b‘, 2, ‘d‘]
8 #l1: [‘a‘, 1, ‘c‘, ‘b‘, 2, ‘b‘, ‘c‘, ‘d‘, ‘a‘]
9 #