Python中非常实用的一些功能和函数分享

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:

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

import glob

# get all py files
files = glob.glob('*.py')
print files

# Output
# ['arg.py', 'g.py', 'shut.py', 'test.py']

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

import 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

import logging, inspect

logging.basicConfig(level=logging.INFO,
    format='%(asctime)s %(levelname)-8s %(filename)s:%(lineno)-4d: %(message)s',
    datefmt='%m-%d %H:%M',
    )
logging.debug('A debug message')
logging.info('Some information')
logging.warning('A shot across the bow')

def test():
    frame,filename,line_number,function_name,lines,index=\
        inspect.getouterframes(inspect.currentframe())[1]
    print(frame,filename,line_number,function_name,lines,index)

test()

# Should print the following (with current date/time of course)
#10-19 19:57 INFO     test.py:9   : Some information
#10-19 19:57 WARNING  test.py:10  : A shot across the bow
#(, 'C:/xxx/pyfunc/magic.py', 16, '', ['test()\n'], 0)

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
你可能会注意到，即使字符串是唯一的，但它们后边的几个字符看起来很相似。这是因为生成的字符串与电脑的MAC地址是相联系的。

为了减少重复的情况，你可以使用这两个函数。

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

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']

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'="">

import zlib

string =  """   Lorem ipsum dolor sit amet, consectetu
                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

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