list去重

去除list中重复的元素

a = [1,2,3,4,5,6,7,2,1,3,5,6,7,8]

方法一：enumerate()

a = [item for index,item in enumerate(a) if index==a.index(item)][1,2,3,4,5,6,7,8]

注：Python的内置函数 enumerate(index,item,索引起始值)

统计文件的行数：

count = -1for index,item in enumerate(open(filename,'r'))    count += 1

方法二：for循环

new_list = []for i in a:    if i not in new_list:        new_list.append(i)print(new_list)

方法三：set()

new_list = list(set(a))

方法四：lambda reduce()

func = lambda x,y:x if y in x else x+[y]reduce(func,[[],]+a)

方法五：itertools模块

import itertoolsa = [1,2,3,4,5,6,7,2,1,3,5,6,7,8]a.sort()new_group = itertools.groupby(a)for index,item in new_group:    print(index)

方法六：函数

def delRepeat(list):    for i in list:        while list.count(i)>1:            del list[list.index(i)]    return list

方法七：快速排序

如下，只需要把集合修改为单值元素

import randoma = [1,2,3,4,5,6,7,2,1,3,5,6,7,8]def qsort(a):    if len(a)<2:return a    pivot_element = random.choice(a)    small = [i for i in a if i ==pivot_elelment]    large = [i for in in a if i>pivot_element]    return qsort(small)+[pivot_element]+qsort(large)print(qsort(a))

方法八：fromkeys（）

new_list = {}.fromkeys(a).keys()print new_list