【零基础向】关于列表的几个有趣的知识

xiaofan1228

1. s = "Sophie and Jimmy"
   
2. print(list(s))
   
3. # ['S', 'o', 'p', 'h', 'i', 'e', ' ', 'a', 'n', 'd', ' ', 'J', 'i', 'm', 'm', 'y']
   
4. print(s.split(" "))
   
5. # ['Sophie', 'and', 'Jimmy']
   
6. L = "love"
   
7. l = list(L)
   
8. print(''.join(l))
   
9. # love
   
10. print("_".join(l))
    
11. # l_o_v_e
    
12. print(s.join(l))
    
13. # lSophie and JimmyoSophie and JimmyvSophie and Jimmye
    
14. 
    
15. # append 的弊端 side effects：赋值语句不能拷贝列表，而是增加了列表对象的指针
    
16. 
    
17. warm = ["red", "yellow", "orange"]
    
18. hot = warm
    
19. hot.append("pink")
    
20. print(hot)
    
21. print(warm)
    
22. # ['red', 'yellow', 'orange', 'pink']
    
23. # ['red', 'yellow', 'orange', 'pink']
    
24. 
    
25. # 这种情况可以被继承
    
26. 
    
27. warm = ["red", "yellow", "orange"]
    
28. hot = ["red"]
    
29. brightcolors = [warm]
    
30. brightcolors.append(hot)
    
31. print(brightcolors)
    
32. hot.append("pink")
    
33. print(hot)
    
34. print(brightcolors)
    
35. 
    
36. 
    
37. # [['red', 'yellow', 'orange'], ['red']]
    
38. # ['red', 'pink']
    
39. # [['red', 'yellow', 'orange'], ['red', 'pink']]
    
40. 
    
41. # 迭代过程中index counter并不会随着列表的改变而改变
    
42. 
    
43. def remove_dups(L1, L2):
    
44.     for e in L1:
    
45.         if e in L2:
    
46.             L1.remove(e)
    
47. 
    
48. 
    
49. L1 = [1, 2, 3, 4]
    
50. L2 = [1, 2, 5, 6]
    
51. remove_dups(L1, L2)
    
52. print(L1)
    
53. # [2, 3, 4] 在第一次for 循环中 L1[0] = 1被删除，此时L1 = [2,3,4], 然后索引直接进入L1[1] = 3，跳过了L[0] = 2
    
54. # 如果想维持或拷贝原列表，可以采用切片方式
    
55. 
    
56. cool = ["blue", "green", "grey"]
    
57. chill = cool[:]
    
58. chill.append("black")
    
59. print(chill)
    
60. print(cool)
    
61. # ['blue', 'green', 'grey', 'black']
    
62. # ['blue', 'green', 'grey']
    
63. 
    
64. def remove_dups_1(L1, L2):
    
65.     L1_copy = L1[:]
    
66.     for e in L1_copy:
    
67.         if e in L2:
    
68.             L1.remove(e)
    
69. 
    
70. 
    
71. L3 = [1, 2, 3, 4]
    
72. L4 = [1, 2, 5, 6]
    
73. remove_dups_1(L3, L4)
    
74. print(L3)
    
75. # [3, 4]

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