你所不知道的python特点及语句

1.自定义可选参数

方法1:自定义可选参数

def function(arg1="",arg2=""):    print "arg1: {0}".format(arg1)    print "arg2: {0}".format(arg2)function("Hello", "World")# prints args1: Hello# prints args2: Worldfunction()# prints args1:# prints args2

方法2：元组实现，类似java func(Object arg…)

def foo(*args): # just use "*" to collect all remaining arguments into a tuple    numargs = len(args)    print "Number of arguments: {0}".format(numargs)    for i, x in enumerate(args):        print "Argument {0} is: {1}".format(i,x)foo()# Number of arguments: 0foo("hello")# Number of arguments: 1# Argument 0 is: hellofoo("hello","World","Again")# Number of arguments: 3# Argument 0 is: hello# Argument 1 is: World# Argument 2 is: Again

使用Glob()查找文件

Glob()可以说是一个更强大版本的listdir()函数(它可以让你通过使用模式匹配来搜索文件)

#模糊搜索import glob# get all py filesfiles = glob.glob('*.py')print files# Output# ['arg.py', 'g.py', 'shut.py', 'test.py']

多类型搜索

import itertools as it, globdef multiple_file_types(*patterns):    return it.chain.from_iterable(glob.glob(pattern) for pattern in patterns)for filename in multiple_file_types("*.txt", "*.py"): # add as many filetype arguements    print filename# output#=========## test.txt# arg.py# g.py# shut.py# test.py

调用realpath()函数显示绝对路径

mport itertools as it, glob, osdef multiple_file_types(*patterns):    return it.chain.from_iterable(glob.glob(pattern) for pattern in patterns)for filename in multiple_file_types("*.txt", "*.py"): # add as many filetype arguements    realpath = os.path.realpath(filename)    print realpath# output#=========## C:\xxx\pyfunc\test.txt# C:\xxx\pyfunc\arg.py# C:\xxx\pyfunc\g.py# C:\xxx\pyfunc\shut.py# C:\xxx\pyfunc\test.py

生成唯一id

1.UUID

import uuidresult = uuid.uuid1()print result# output => various attempts# 9e177ec0-65b6-11e3-b2d0-e4d53dfcf61b# be57b880-65b6-11e3-a04d-e4d53dfcf61b# c3b2b90f-65b6-11e3-8c86-e4d53dfcf61b

2.mac地址+key+data

import hmac,hashlibkey='1'data='a'print hmac.new(key, data, hashlib.sha256).hexdigest()m = hashlib.sha1()m.update("The quick brown fox jumps over the lazy dog")print m.hexdigest()# c6e693d0b35805080632bc2469e1154a8d1072a86557778c27a01329630f8917# 2fd4e1c67a2d28fced849ee1bb76e7391b93eb12

序列号

1.python以前的序列化方法:

import picklevariable = ['hello', 42, [1,'two'],'apple']# serialize contentfile = open('serial.txt','w')serialized_obj = pickle.dumps(variable)file.write(serialized_obj)file.close()# unserialize to produce original contenttarget = open('serial.txt','r')myObj = pickle.load(target)print serialized_objprint myObj#output# (lp0# S'hello'# p1# aI42# a(lp2# I1# aS'two'# p3# aaS'apple'# p4# a.# ['hello', 42, [1, 'two'], 'apple']

2.流行的json序列化方法

import jsonvariable = ['hello', 42, [1,'two'],'apple']print "Original {0} - {1}".format(variable,type(variable))# encodingencode = json.dumps(variable)print "Encoded {0} - {1}".format(encode,type(encode))#deccodingdecoded = json.loads(encode)print "Decoded {0} - {1}".format(decoded,type(decoded))# output# Original ['hello', 42, [1, 'two'], 'apple'] - <type 'list'=""># Encoded ["hello", 42, [1, "two"], "apple"] - <type 'str'=""># Decoded [u'hello', 42, [1, u'two'], u'apple'] - <type 'list'="">

字符串压缩

import zlibstring =  """   Lorem ipsum dolor sit amet, consectetur                adipiscing elit. Nunc ut elit id mi ultricies                adipiscing. Nulla facilisi. Praesent pulvinar,                sapien vel feugiat vestibulum, nulla dui pretium orci,                non ultricies elit lacus quis ante. Lorem ipsum dolor                sit amet, consectetur adipiscing elit. Aliquam                pretium ullamcorper urna quis iaculis. Etiam ac massa                sed turpis tempor luctus. Curabitur sed nibh eu elit                mollis congue. Praesent ipsum diam, consectetur vitae                ornare a, aliquam a nunc. In id magna pellentesque                tellus posuere adipiscing. Sed non mi metus, at lacinia                augue. Sed magna nisi, ornare in mollis in, mollis                sed nunc. Etiam at justo in leo congue mollis.                Nullam in neque eget metus hendrerit scelerisque                eu non enim. Ut malesuada lacus eu nulla bibendum                id euismod urna sodales. """print "Original Size: {0}".format(len(string))compressed = zlib.compress(string)print "Compressed Size: {0}".format(len(compressed))decompressed = zlib.decompress(compressed)print "Decompressed Size: {0}".format(len(decompressed))# output# Original Size: 1022# Compressed Size: 423# Decompressed Size: 1022

注册Shutdown函数

脚本运行完毕后会执行shutdown函数:

import atexitimport timeimport mathdef microtime(get_as_float = False) :    if get_as_float:        return time.time()    else:        return '%f %d' % math.modf(time.time())start_time = microtime(False)atexit.register(start_time)def shutdown():    global start_time    print "Execution took: {0} seconds".format(start_time)atexit.register(shutdown)# Execution took: 0.297000 1387135607 seconds# Error in atexit._run_exitfuncs:# Traceback (most recent call last):#   File "C:\Python27\lib\atexit.py", line 24, in _run_exitfuncs#     func(*targs, **kargs)# TypeError: 'str' object is not callable# Error in sys.exitfunc:# Traceback (most recent call last):#   File "C:\Python27\lib\atexit.py", line 24, in _run_exitfuncs#     func(*targs, **kargs)# TypeError: 'str' object is not callable

else高级用法

1.用于非正常循环结束

def print_prime(n):    for i in xrange(2, n):        # found = True        for j in xrange(2, i):            if i % j == 0:                 # found = False                 break        else:# ==> if has break            print "{} it's a prime number".format(i)        # if found:                  # print "{} it's a prime number".format(i)print_prime(7)2 it's a prime number3 it's a prime number5 it's a prime number

2.try except没有出现except

def my_to_int(str_param):    try:        print int(str_param)    except ValueError:        print 'cannot convert {} to a integer'.format(str_param)    else:        print 'convert {} to integer successfully'.format(str_param)my_to_int("123")my_to_int("me123")123convert 123 to integer successfullycannot convert me123 to a integer

博客出处

原文:
http://python.jobbole.com/84228/

http://python.jobbole.com/84270/