python 删除list中重复元素

list = [1,1,3,4,6,3,7]

　　1.

for s in list:
    if list.count(s) >1:
        list.remove(s)

　　2.

list2=[]
for s in list:
    if s not in list2:
        list2.append(s)

print list2

　　3.

b = {}
b = b.fromkeys(list)
print b.keys()

　4.set(list)