Python常用指令

import timeimport ostime.sleep()    #延时time.clock()    #第一次调用返回程序运行的实际时间；第二次调用返回第一次调用后到这次调用的时间间隔time.time()     #当前时间戳time.ctime()    #当前时间的字符串形式os.getcwd()     #获取当前脚本路径os.chdir('D:\\') #修改当前路径os.linesep      #当前环境下的换行分隔符os.system('pause')  #按任意键继续

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执行外部.py文件

os.chdir(r'D:\test.py')exec(compile(open(r'D:\test.py').read(),r'D:\test.py','exec'))

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带index的枚举

for index, item in enumerate(items):    print(index, item)

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字符串合并

l = ['one', 'two', 'three']s = ''.join(l)    #s='onetwothree'

字符串分割用str.split(sep=None, maxsplit=-1)

'1,2,,3,'.split(',')#输出['1', '2', '', '3', '']'   1   2   3   '.split()#输出['1', '2', '3'] 自动合并空格items = 'zero one two three'.split()#方便的单词list初始化

行分割用str.splitlines([keepends])
自动舍弃空行，常用于文件操作
更复杂的要求可用re.split(pattern, string, maxsplit=0, flags=0)

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显示正则表达式推导树

re.compile("^\[font(?:=(?P<size>[-+][0-9]{1,2}))?\](.*?)[/font]",    re.DEBUG)

添加注释的正则表达式

pattern = """^                   # beginning of stringM{0,4}              # thousands - 0 to 4 M's(CM|CD|D?C{0,3})    # hundreds - 900 (CM), 400 (CD), 0-300 (0 to 3 C's), or 500-800 (D, followed by 0 to 3 C's)(XC|XL|L?X{0,3})    # tens - 90 (XC), 40 (XL), 0-30 (0 to 3 X's), or 50-80 (L, followed by 0 to 3 X's)(IX|IV|V?I{0,3})    # ones - 9 (IX), 4 (IV), 0-3 (0 to 3 I's), or 5-8 (V, followed by 0 to 3 I's)$                   # end of string"""re.search(pattern, 'M', re.VERBOSE)

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从字符串创建对应名字的类对象

class ButtonFactory():    def create_button(self, typ):        targetclass = typ.capitalize()        return globals()[targetclass]()

使用方法

button_obj = ButtonFactory()button_obj.create_button('button').

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线程之间队列

def worker():    while True:        item = q.get()        do_work(item)        q.task_done()q = Queue()for i in range(num_worker_threads):     t = Thread(target=worker)     t.daemon = True     t.start()for item in source():    q.put(item)q.join()#Queue除了提供常规的阻塞/非阻塞put() get()外，还实现了一组取决于计数的阻塞机制：每当添加元素时计数增加1，task_down()计数减1，join()阻塞直至计数归零

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参数列表

def draw(x, y):    # do some magicpoint_foo = (3, 4)point_bar = {'y': 4, 'x': 3}draw_point(*point_foo)draw_point(**point_bar) #对应参数名的字典

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tuple多赋值与深度拷贝

import copym = [1, 2, [3, 4]]a = mb = m.copy()b1, b2, b3 = mc1, c2, c3 = copy.deepcopy(m)m[1] = 20m[2][0] = 30print(a)print(b)print(b1, b2, b3)print(c1, c2, c3)

运行结果：

[1, 20, [30, 4]][1, 2, [30, 4]]1 2 [30, 4]1 2 [3, 4]

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pprint.pprint可产生相应对象的构造字符串
若更为精细地进行对象序列化，则使用Pickling
序列化

import pickledata = {'foo': [1,2,3],                'bar': ('Hello', 'world!'),                'baz': True}jar = open('data.pkl', 'wb')pickle.dump(data, jar) # 将pickle后的数据写入jar文件jar.close()

反序列化

import picklepkl_file = open('data.pkl', 'rb')data = pickle.load(pkl_file)print datapkl_file.close()

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total = sum([num * num for num in range(1, 101)])#lazy生成器total = sum(num * num for num in xrange(1, 101))

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集合操作

>>> a = set([1,2,3,4])>>> b = set([3,4,5,6])>>> a | b # Union{1, 2, 3, 4, 5, 6}>>> a & b # Intersection{3, 4}>>> a < b # SubsetFalse>>> a - b # Difference{1, 2}>>> a ^ b # Symmetric Difference{1, 2, 5, 6}

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模块结构规范

"""module docstring"""# imports# constants# exception classes# interface functions# classes# internal functions & classesdef main(...):    ...if __name__ == '__main__':    status = main()    sys.exit(status)

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magic function内置函数隐含调用列表
http://www.rafekettler.com/magicmethods.html
常用：

__getattr__(self, name):     self.name 当name不存在时__setattr__(self, name, val)    self.name = val 当name不存在时__iter__(self)      for x in self   迭代器__getitem__(self, key)      self[key] 下标索引访问__setitem__(self, key, val)     self[key] =val 下标索引赋值__index__(self)    x[self] 作为数组下标时