《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：

#首字母相同的男生女生
girls = ['alice', 'bernice', 'clarice']
boys = ['chris', 'arnold', 'bob']
lettergirls = {}
for girl in girls:
    lettergirls.setdefault(girl[0], []).append(girl)
print([b+'+'+ｇ for b in boys for g in lettergirls[b[0]]])

#斐波那契数列
def fibs(num):
    result = [1, 2]
    for i in range(num - 2):
        result.append(result[-2] + result[-1])
    return result
print(fibs(20))

#存储全名的字典
def init(data):
    data['first'] = {}
    data['middle'] = {}
    data['last'] = {}
def lookup(data, label, name):
    return data[label].get(name)
def store(data, full_name):
    names = full_name.split()
    if len(names) == 2:
        names.insert(1, ' ')
    labels = ('first', 'middle', 'last')
    for label, name = zip(labels, names):
        people = lookup(data, label, name)
        if people:
            people.append(full_name)
        else:
            data[label][name] = [full_name]

#递归经典：阶乘、幂、二分查找
def search(sequence, number, lower, upper):
    if lower == upper:
        assert number == sequence[upper]
        return upper
    else:
        middle = (lower + upper) // 2
        if number > sequence[middle]:
            return search(sequence, number, middle + 1, upper)
        else:
            return search(sequence, number, lower, middle)

#模拟实现无穷算术序列
def checkIndex(key):
    if not isinstance(key, (int, long)):
        raise TypeError
    if key < 0:
        raise IndexError
class ArithmeticSequence:
    def __init__(self, start = 0, step = 1):
        self.start = start
        self.step = step
        self.changed = {}
    def __getitem__(self, key):
        checkIndex(key)
        try:
            return self.changed[key]
        except KeyError:
            return self.start + key * self.step
    def __setitem__(self, key, value):
        checkIndex(key)
        self.changed[key] = value

#基本的序列与映射规则
def checkIndex(key):
    if not isinstance(key, (int, long)):
        raise TypeError
    if key < 0:
        raise IndexError
class ArithmeticSequence:
    def __init__(self, start = 0, step = 1):
        self.start = start
        self.step = step
        self.changed = {}
    def __getitem__(self, key):
        checkIndex(key)
        try:
            return self.changed[key]
        except KeyError:
            return self.start + key * self.step
    def __setitem__(self, key, value):
        checkIndex(key)
        self.changed[key] = value
#带有访问计数的列表
class CounterList(list):
    def __init__(self, *agrs):
        super(CounterList, self).__init__(*args)
        self.counter = 0
    def __getitem__(self, index):
        self.counter += 1
        return super(CounterList, self).__getitem__(index)