Python-List

Posted 2020-11-17 徐李帅

 1 切片:取多个元素
 2 >>> names = ["A","B","C","D","E","F"]
 3 >>> names[1:4]  #取下标1至下标4之间的数字，包括1，不包括4
 4 [‘B‘, C‘, ‘D‘]
 5 >>> names[1:-1] #取下标1至-1的值，不包括-1
 6 [‘B‘, ‘C‘, ‘D‘, ‘E‘]
 7 >>> names[0:3] 
 8 [‘A‘, ‘B‘, ‘C‘]
 9 >>> names[:3] #如果是从头开始取，0可以忽略，跟上句效果一样
10 [‘A‘, ‘B‘, ‘C‘]
11 >>> names[3:] #如果想取最后一个，必须不能写-1，只能这么写
12 [‘D‘, ‘E‘, ‘F‘] 
13 >>> names[3:-1] #这样-1就不会被包含了
14 [‘D‘, ‘E‘]
15 >>> names[0::2] #后面的2是代表，每隔一个元素，就取一个
16 [‘A‘, ‘C‘, ‘E‘] 
17 >>> names[::2] #和上句效果一样
18 [‘A‘, ‘C‘, ‘E‘] 
19  
20 追加
21 >>> names
22 [‘A‘, ‘B‘, ‘C‘, ‘D‘, ‘E‘, ‘F‘]
23 >>> names.append(‘G‘)  #在最后面插入值
24 [‘A‘, ‘B‘, ‘C‘, ‘D‘, ‘E‘, ‘F‘, ‘G‘]
25 
26 
27 插入
28 >>> names
29 [‘A‘, ‘B‘, ‘C‘, ‘D‘, ‘E‘, ‘F‘ , ‘G‘]
30 >>> names.insert(2,‘H‘)  #在C前面插入H
31 [‘A‘, ‘B‘, ‘G‘, ‘C‘, ‘D‘, ‘E‘, ‘F‘ , ‘G‘]
32 
33 修改
34 >>> names
35 [‘A‘, ‘B‘, ‘C‘, ‘D‘, ‘E‘, ‘F‘ , ‘G‘]
36 >>> names[2] = ‘H‘  #把下标2替换掉
37 [‘A‘, ‘B‘, ‘H‘, ‘D‘, ‘E‘, ‘F‘ , ‘G‘]
38 
39 删除
40 >>> names
41 [‘A‘, ‘B‘, ‘C‘, ‘D‘, ‘E‘, ‘F‘ , ‘G‘]
42 >>> del names[2]  #把下标2删除掉
43 [‘A‘, ‘B‘, ‘D‘, ‘E‘, ‘F‘ , ‘G‘]
44 >>> names.remove(‘B‘)  #删除指定元素
45 [‘A‘, ‘D‘, ‘E‘, ‘F‘ , ‘G‘]
46 >>> names.pop()  #删除列表最后一个值
47 
48 扩展
49 >>> names1
50 [‘A‘, ‘B‘, ‘C‘, ‘D‘, ‘E‘, ‘F‘ , ‘G‘]
51 >>> names2 = [‘H‘,‘I‘,‘J‘]
52 >>> names1.extend(names2)
53 >>> names1
54 [‘A‘, ‘B‘, ‘C‘, ‘D‘, ‘E‘, ‘F‘ , ‘G‘, ‘H‘, ‘I‘, ‘J‘]
55 
56 拷贝
57 >>> names
58 [‘A‘, ‘B‘, ‘C‘, ‘D‘, ‘E‘, ‘F‘ , ‘G‘]
59 >>> name_copy = names.copy()
60 >>> name_copy
61 [‘A‘, ‘B‘, ‘C‘, ‘D‘, ‘E‘, ‘F‘ , ‘G‘]
62 
63 统计
64 >>> names
65 [‘A‘, ‘B‘, ‘C‘, ‘D‘, ‘E‘, ‘F‘ , ‘G‘, ‘C‘]
66 >>> names.count(‘C‘)
67 2
68 
69 获取下标
70 >>> names
71 [‘A‘, ‘B‘, ‘C‘, ‘D‘, ‘E‘, ‘F‘ , ‘G‘, ‘C‘]
72 >>> names.index(‘C‘)
73 2
74 
75 排序&翻转
76 [‘Alex‘, ‘Amy‘, ‘Amy‘, ‘Tenglan‘, ‘Tom‘, ‘1‘, ‘2‘, ‘3‘]
77 >>> names.sort() #python3 里不同数据类型不能放在一起排序了
78 >>> names
79 [‘1‘, ‘2‘, ‘3‘, ‘Alex‘, ‘Amy‘, ‘Amy‘, ‘Tenglan‘, ‘Tom‘]
80 
81 >>> names.reverse() #反转
82 >>> names
83 [‘Tom‘, ‘Tenglan‘, ‘Amy‘, ‘Amy‘, ‘Alex‘, ‘3‘, ‘2‘, ‘1‘]