【006】Python筛选多个字典中相同的键

Aojacy

1. '''
   
2. 目的：筛选出N个字典中都出现相同的键
   
3. '''
   
4. #方法一：for循环（执行效率低）
   
5. from random import randint,sample
   
6. d1 = {x:randint(1,6) for x in sample(['aa','bb','cc','dd','ee'],randint(1,5))}
   
7. d2 = {x:randint(1,6) for x in sample(['aa','bb','cc','dd','ee'],randint(1,5))}
   
8. d3 = {x:randint(1,6) for x in sample(['aa','bb','cc','dd','ee'],randint(1,5))}
   
9. print(d1)
   
10. print(d2)
    
11. print(d3)
    
12. res = []
    
13. for x in d1:
    
14.     if x in d2 and x in d3:
    
15.         res.append(x)
    
16. print(res)
    
17. 
    
18. #方法二：高阶函数 map + reduce
    
19. from random import randint,sample
    
20. from functools import reduce
    
21. d1 = {x:randint(1,6) for x in sample(['aa','bb','cc','dd','ee'],randint(1,5))}
    
22. d2 = {x:randint(1,6) for x in sample(['aa','bb','cc','dd','ee'],randint(1,5))}
    
23. d3 = {x:randint(1,6) for x in sample(['aa','bb','cc','dd','ee'],randint(1,5))}
    
24. print(d1)
    
25. print(d2)
    
26. print(d3)
    
27. 
    
28. #将每个字典中的 键 筛选出来
    
29. r = map(dict.keys, [d1,d2,d3])
    
30. print(list(r))
    
31. 
    
32. #reduce迭代筛选（每次&运算后的结果作为x的新值，效率高）
    
33. res = reduce(lambda x , y : x & y ,map(dict.keys, [d1,d2,d3]))
    
34. print(res)
    
35. '''
    
36. 提问与思考：
    
37. 1、 直接遍历字典只能遍历键key，items() 函数以列表返回可遍历的(键, 值) 元组数组
    
38. 2、reduce的传入函数必须接收两个参数
    
39. '''

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