List相关操作小例子

获取list的下标和值

>>> mylist = ['a', 'b', 'c', 'd'] >>> for index, value in enumerate(mylist): ... print(index, value) ... 0 a 1 b 2 c 3 d >>> 

删除list中的空字符

list1 = ['1', '','2', '3', ' ', ' 4 ', ' 5', ' ','6 ', '', ' ',None, '7'] print(list1) list2 = list(filter(None, list1)) print(list2) # ['1', '2', '3', ' ', ' 4 ', ' 5', ' ', '6 ', ' ', '7'] list3 = [x.strip() for x in list2] print(list3) # ['1', '2', '3', '', '4', '5', '', '6', '', '7'] list4 = list(filter(None, list3)) print(list4) # ['1', '2', '3', '4', '5', '6', '7'] 

删除list元素

使用remove、pop和del方法参删除list中的某个元素

>>> mylist = ['a', 'b', 'c', 'd','e','f','g','h'] >>> mylist.remove('a') >>> mylist ['b', 'c', 'd', 'e', 'f', 'g', 'h'] >>> mylist.pop(0) 'b' >>> mylist ['c', 'd', 'e', 'f', 'g', 'h'] >>> del mylist[0] >>> mylist ['d', 'e', 'f', 'g', 'h'] >>> del mylist[0:2] >>> mylist ['f', 'g', 'h'] >>> del mylist >>> mylist Traceback (most recent call last): File "<stdin>", line 1, in <module> NameError: name 'mylist' is not defined >>> 

计算中位数

def get_median(data): data.sort() half = len(data) // 2 return (data[half] + data[~half]) / 2 

将字符串list转换为int

>>> test_list = ['1', '4', '3', '6', '7'] >>> test_list = list(map(int, test_list)) >>> test_list [1, 4, 3, 6, 7] >>> 

合并、连接字符串list

>>> test_list = ['192', '168', '0', '1'] >>> test_list = '.'.join(test_list) >>> test_list '192.168.0.1' >>> 

取多个字符串/list交集

>>> a = ['123','234','1253'] >>> list(reduce(lambda x,y : set(x) & set(y), a)) ['2', '3'] >>> b = [[1,2,3],[1,2],[1,2,3,4],[12,1,2]] >>> list(reduce(lambda x,y : set(x) & set(y), b)) [1, 2] 

合并字典value值

>>> mydict = {0:"hello ", 1:"world"} >>> mylist =reduce(lambda x, y : x + y, mydict.values()) >>> mylist 'hello world' >>> mydict = {0:[1,2,3,4], 1:[2,3,4,5,6]} >>> mylist = list(reduce(lambda x, y : x + y, mydict.values())) >>> mylist [1, 2, 3, 4, 2, 3, 4, 5, 6] >>> field_counters = dict(Counter(mylist)) >>> field_counters {1: 1, 2: 2, 3: 2, 4: 2, 5: 1, 6: 1} 

列表排列组合

列表排列组合可以使用迭代器模块itertools

列表排列

import itertools l = [1, 2, 3] print(list(itertools.permutations(l, 2))) print(list(itertools.permutations(l, 3))) 

结果：

[(1, 2), (1, 3), (2, 1), (2, 3), (3, 1), (3, 2)] [(1, 2, 3), (1, 3, 2), (2, 1, 3), (2, 3, 1), (3, 1, 2), (3, 2, 1)] 

组合

import itertools l = [1, 2, 3] print(list(itertools.combinations(l, 2))) 

结果：

[(1, 2), (1, 3), (2, 3)] 

多个列表元素组合：笛卡尔积

两个列表元素两两组合：

import itertools l = [1, 2, 3] l1 = [11, 12, 13] l2 = [21, 22, 23] # 笛卡尔积 print(list(itertools.product(l, l))) print(list(itertools.product(l, repeat=2))) print(list(itertools.product(l1, l2))) 

结果：

[(1, 1), (1, 2), (1, 3), (2, 1), (2, 2), (2, 3), (3, 1), (3, 2), (3, 3)] [(1, 1), (1, 2), (1, 3), (2, 1), (2, 2), (2, 3), (3, 1), (3, 2), (3, 3)] [(11, 21), (11, 22), (11, 23), (12, 21), (12, 22), (12, 23), (13, 21), (13, 22), (13, 23)]