解包与压缩 | *sequence, reduce | reduce快速字典重新整理,参考#3

 1 '''
 2 解包与压缩
 3 *sequence,reduce
 4 reduce快速字典重新整理,参考#3
 5 '''
 6 from functools import reduce
 7 primes = [1,2,3,4]
 8 def product(*numbers):
 9     p = reduce(lambda x, y: x*10+y, numbers)
10     print(numbers)
11     print(p)
12 p=product(*primes)  ##*解压,reduce()压缩
13 p=product(primes,[1])
14 
15 '''
16 reduce官方文档定义(部分):'一次处理两个参数'
17 Apply a function of two arguments cumulatively to the items of a sequence,
18 from left to right, so as to reduce the sequence to a single value.
19 ————————————————
20 
21 在迭代sequence(tuple ,list ,dictionary, string等可迭代物)的过程中,
22 reduce工作过程:
23 1、首先把 前两个元素传给 函数参数,函数加工后,
24 2、然后把得到的结果和第三个元素作为两个参数传给函数参数,
25 3、函数加工后得到的结果又和第四个元素作为两个参数传给函数参数,依次类推
26 '''
27 #1
28 numbers = [1,2,3,4]
29 p = reduce(lambda x, y: x*10+y, numbers,1)
30 print(p)#没1输出1234,有1输出11234
31 
32 #2
33 from functools import reduce
34 scientists =({'name':'Alan Turing', 'age':105, 'gender':'male'},
35              {'name':'Dennis Ritchie', 'age':76, 'gender':'male'},
36              {'name':'Ada Lovelace', 'age':202, 'gender':'female'},
37              {'name':'Frances E. Allen', 'age':84, 'gender':'female'})
38 def reducer(accumulator , value):
39     #print(accumulator , value)
40     sum = accumulator + value['age']
41     return sum
42 total_age = reduce(reducer, scientists, 0)#0作为reducer初始值,当wequence为空;或作为第一个值
43 print(total_age)#输出467
44 #可用一行下面行数实现
45 sum([x['age'] for x in scientists ])#467
46 
47 #3  reduce快速字典重新整理,
48 from functools import reduce
49 scientists =({'name':'Alan Turing', 'age':105, 'gender':'male'},
50              {'name':'Dennis Ritchie', 'age':76, 'gender':'male'},
51              {'name':'Ada Lovelace', 'age':202, 'gender':'female'},
52              {'name':'Frances E. Allen', 'age':84, 'gender':'female'})
53 def group_by_gender(accumulator , value):
54     accumulator[value['gender']].append(value['name'])
55     return accumulator
56 grouped = reduce(group_by_gender, scientists, {'male':[], 'female':[]})
57 print(grouped)

 

posted @ 2023-05-04 15:51  Aneverforget  阅读(10)  评论(0编辑  收藏  举报