你所不知道的python特点及语句

àì夳堔傛蜴生んèń 2022-08-20 05:20 143阅读 0赞

# 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: World
    
    function()
    # 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: 0
    
    foo("hello")
    # Number of arguments: 1
    # Argument 0 is: hello
    
    foo("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 files
    files = glob.glob('*.py')
    print files
    
    # Output
    # ['arg.py', 'g.py', 'shut.py', 'test.py']

多类型搜索

import itertools as it, glob
    
    def 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, os
    
    def 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 uuid
    result = 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,hashlib
    key='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 pickle
    
    variable = ['hello', 42, [1,'two'],'apple']
    
    # serialize content
    file = open('serial.txt','w')
    serialized_obj = pickle.dumps(variable)
    file.write(serialized_obj)
    file.close()
    
    # unserialize to produce original content
    target = open('serial.txt','r')
    myObj = pickle.load(target)
    
    print serialized_obj
    print 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 json
    
    variable = ['hello', 42, [1,'two'],'apple']
    print "Original {0} - {1}".format(variable,type(variable))
    
    # encoding
    encode = json.dumps(variable)
    print "Encoded {0} - {1}".format(encode,type(encode))
    
    #deccoding
    decoded = 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 zlib
    
    string =  """ 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 atexit
    import time
    import math
    
    def 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 number
    3 it's a prime number
    5 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")
    
    123
    convert 123 to integer successfully
    cannot convert me123 to a integer

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原文:  
[http://python.jobbole.com/84228/][http_python.jobbole.com_84228]

[http://python.jobbole.com/84270/][http_python.jobbole.com_84270]

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