《Python基础教程》一点笔记

这本书还是月初的时候翻了翻，看了前十章左右就发现这本书写的比较烂，翻译地就更烂了，讲的内容其实没有抓住重点。

下面是看的时候记得几小段代码：

 1 #首字母相同的男生女生
 2 girls = ['alice', 'bernice', 'clarice']
 3 boys = ['chris', 'arnold', 'bob']
 4 lettergirls = {}
 5 for girl in girls:
 6     lettergirls.setdefault(girl[0], []).append(girl)
 7 print([b+'+'+ｇ for b in boys for g in lettergirls[b[0]]])
 8 
 9 #斐波那契数列
10 def fibs(num):
11     result = [1, 2]
12     for i in range(num - 2):
13         result.append(result[-2] + result[-1])
14     return result
15 print(fibs(20))
16 
17 #存储全名的字典
18 def init(data):
19     data['first'] = {}
20     data['middle'] = {}
21     data['last'] = {}
22 def lookup(data, label, name):
23     return data[label].get(name)
24 def store(data, full_name):
25     names = full_name.split()
26     if len(names) == 2:
27         names.insert(1, ' ')
28     labels = ('first', 'middle', 'last')
29     for label, name = zip(labels, names):
30         people = lookup(data, label, name)
31         if people:
32             people.append(full_name)
33         else:
34             data[label][name] = [full_name]
35 
36 #递归经典：阶乘、幂、二分查找
37 def search(sequence, number, lower, upper):
38     if lower == upper:
39         assert number == sequence[upper]
40         return upper
41     else:
42         middle = (lower + upper) // 2
43         if number > sequence[middle]:
44             return search(sequence, number, middle + 1, upper)
45         else:
46             return search(sequence, number, lower, middle)
47 
48 #模拟实现无穷算术序列
49 def checkIndex(key):
50     if not isinstance(key, (int, long)):
51         raise TypeError
52     if key < 0:
53         raise IndexError
54 class ArithmeticSequence:
55     def __init__(self, start = 0, step = 1):
56         self.start = start
57         self.step = step
58         self.changed = {}
59     def __getitem__(self, key):
60         checkIndex(key)
61         try:
62             return self.changed[key]
63         except KeyError:
64             return self.start + key * self.step
65     def __setitem__(self, key, value):
66         checkIndex(key)
67         self.changed[key] = value

 1 #基本的序列与映射规则
 2 def checkIndex(key):
 3     if not isinstance(key, (int, long)):
 4         raise TypeError
 5     if key < 0:
 6         raise IndexError
 7 class ArithmeticSequence:
 8     def __init__(self, start = 0, step = 1):
 9         self.start = start
10         self.step = step
11         self.changed = {}
12     def __getitem__(self, key):
13         checkIndex(key)
14         try:
15             return self.changed[key]
16         except KeyError:
17             return self.start + key * self.step
18     def __setitem__(self, key, value):
19         checkIndex(key)
20         self.changed[key] = value
21 #带有访问计数的列表
22 class CounterList(list):
23     def __init__(self, *agrs):
24         super(CounterList, self).__init__(*args)
25         self.counter = 0
26     def __getitem__(self, index):
27         self.counter += 1
28         return super(CounterList, self).__getitem__(index)