1.set()方法

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

y = list(set(x))

print(y)

```

[1, 2, 3, 4, 5]

```

2.

x = ['b','c','d','b','c','a','a']

y = {}.fromkeys(x).keys()

print(y)

```

dict_keys(['b', 'c', 'd', 'a'])

```

3. set() 方法会改变列表顺序

z = list(set(x))

print(z)

```

['d', 'a', 'c', 'b']

```

4. 使用sort(),使之与原来的相同

z.sort(key=x.index)

z

```

['b', 'c', 'd', 'a']

```

5.

l = []

for i in x:

if not i in l:

l.append(i)

print(l)

```

['b', 'c', 'd', 'a']