python列表中删除重复元素的三种方法

listA = ['python','语','言','是','一','门','动','态','语','言']

def deleteDuplicatedElementFromList(list):
        list.sort();
        print("sorted list:%s" % list)
        length = len(list)
        lastItem = list[length - 1]
        for i in range(length - 2,-1,-1):
                currentItem = list[i]
                if currentItem == lastItem:
                        list.remove(currentItem)
                else:
                        lastItem = currentItem
        return list

def deleteDuplicatedElementFromList2(list):
        resultList = []
        for item in list:
                if not item in resultList:
                        resultList.append(item)
        return resultList

def deleteDuplicatedElementFromList3(listA):
        #return list(set(listA))
        return sorted(set(listA), key = listA.index)

print(deleteDuplicatedElementFromList(listA))        
#sorted list:['python', '一', '动', '态', '是', '言', '言', '语', '语', '门']
#['python', '一', '动', '态', '是', '言', '语', '门']
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print(deleteDuplicatedElementFromList2(listA))        
#['python', '语', '言', '是', '一', '门', '动', '态']

print(deleteDuplicatedElementFromList3(listA))        
#['python', '语', '言', '是', '一', '门', '动', '态']