Python编程技巧与应用实例
本文深入探讨了Python编程中的核心概念与实用技巧，通过详细解析常见函数与装饰器的用法，展示如何灵活运用Python解决实际问题。此外，文章还涵盖了Yield、Lambda表达式、内置函数、迭代操作等高级特性，以及数据结构、算法、测试工具等核心知识点，旨在为Python开发者提供全面的技术指南。
Usually used method
__name__
__file__
__doc__
Function
parameter
default parameter
variable parameter
return value
def Foo():
print 'Foo'
def Foo(arg)
print arg
def Foo(arg='tom'):
print arg
#must be put in the end
def Foo(arg1,arg2):
print arg1,arg2
Foo(arg2='alison',arg1='winne')
def Foo(arg,*args):
print arg,args
Foo('ray','neil','tom')
def Foo(**kargs):
print kargs.keys()
print kargs.values()
Foo(k1='sk',k2='alex')Yield
def NeilReadlines():
seek = 0
while True:
with open('E:/temp.txt','r') as f:
f.seek(seek)
data = f.readline()
if data:
seek = f.tell()
yield data
else:
return
for i in NeilReadlines():
print iYield belongs to the decorative device
Three element operation and lambda expression
result = 'gt' if 1>3 else 'lt'
print result
a = lambda x,y:x+y
print a(4,10)Built in function
for example:
#print help()
print dir()
print vars()
#print type()
import temp
import temp
reload(temp)
id([12])
#is
------------------
cmp(2,3)
cmp(2,2)
cmp(2,1)
cmp(10,1)
abs()
bool()
divmod()
max()
min()
sum()
pow(2, 11)
------------------
len()
all()
any()
------------------
chr()
ord()
hex()
oct()
bin()
------------------
print range(10)
print xrange(10)
for i in xrange(10):
print i
for k,v in enumerate([1,2,3,4]):
print k,v
------------------
s= 'i am {0}'
print s.format('alex')
str(1)
------------------
def Function(arg):
print arg
print apply(Function,('aaaa')) #excute function
print map(lambda x:x+1,[1,2,3]) #all
print filter(lambda x: x==1,[1,23,4]) #True sequence
print reduce(lambda x,y:x+y,[1,2,3]) #accumulation
x = [1, 2, 3]
y = [4, 5, 6]
z = [4, 5, 6]
print zip(x, y,z)
------------------
#__import__()
#hasattr()
#delattr()
#getattr()
module = __import__('temp')
print dir(module)
val = hasattr(module, 'version')
print val
------------------
#callable()
#function、class must have "__call__" method
#compile
#eval
com = compile('1+1','','eval')
print eval(com)
#execute sentence
code = "for i in range(0, 10): print i"
cmpcode = compile(code, '', 'exec')
exec cmpcode
code = "print 1"
cmpcode = compile(code, '', 'single')
exec cmpcode
------------------
#isinstance()
#issubclass()
#super()
#staticmethod()More Click me
Popular Modules
first : random (usually used create random number)
for example:
import random
print random.random()
print random.randint(1,2)
print random.randrange(1,10)Application scenarios: generating random verification code
import random
checkcode = ''
for i in range(4):
current = random.randrange(0,4)
if current != i:
temp = chr(random.randint(65,90))
else:
temp = random.randint(0,9)
checkcode += str(temp)
print checkcodesecond:md5 encryption
for example:
import md5
hash = md5.new()
hash.update('admin')
print hash.hexdigest()
import hashlib
hash = hashlib.md5()
hash.update('admin')
print hash.hexdigest()third:serialize and json
for example:
import pickle
dict = {"number1" : {"user" : "wang", "password" : "test123","lock" : "1"},\
"number2" : {"user" : "yang", "password" : "test123","lock" : "2"}
}
#print dict["number1"]["user"]
#this is one way
p_str = pickle.dumps(dict) #this is serialize
print p_str
#this is two way
with open("e:/p_str.pk","w") as fp:
pickle.dump(dict,fp)
p_load = pickle.load("e:/p_str.pk")
print p_load
import json
j_str = json.dumps(dict) #this is serialize
print j_str
#this is two way
with open("e:/j_str.json","w") as fp:
json.dump(dict,fp)
j_load = json.load("e:/j_str.json")
print j_loadfourth:re
for example:
compile
match search findall
group groups
regular expression format:
char：\d \w \t .
times：* + ? {m} {m,n}
fifth:time
import time
#1、time stamp Seconds after January 1, 1970
#3、The tuple contains: year, day, week, etc.... time.struct_time
#4、Formatted string 2014-11-11 11:11
print time.time()
print time.mktime(time.localtime())
print time.gmtime() #Additive time stamp parameter
print time.localtime() #Additive time stamp parameter
print time.strptime('2014-11-11', '%Y-%m-%d')
print time.strftime('%Y-%m-%d') #Default current time
print time.strftime('%Y-%m-%d',time.localtime()) #Default current time
print time.asctime()
print time.asctime(time.localtime())
print time.ctime(time.time())
import datetime
'''
datetime.date：represents date's class。Common attributes are:year, month, day
datetime.time：represents time's class。Common attributes are:hour, minute, second, microsecond
datetime.datetime：represents the date
datetime.timedelta：Represents the time interval, the length between the two time points.
timedelta([days[, seconds[, microseconds[, milliseconds[, minutes[, hours[, weeks]]]]]]])
strftime("%Y-%m-%d")
'''
import datetime
print datetime.datetime.now()
print datetime.datetime.now() - datetime.timedelta(days=5)sixth:sys
sys.argv #Command line arguments List，The first element is the path of
the program itself
sys.exit(n) #Exit the program, when the normal exit :exit(0)
sys.version #Gets the version information of the Python interpreter
sys.maxint
sys.maxunicode
sys.path #Returns the search path for the module,
#using the value of the PYTHONPATH environment variable at initialization time.
sys.platform
sys.stdout.write('please:')
val = sys.stdin.readline()[:-1]
print valseventh:os
os.getcwd() 获取当前工作目录，即当前python脚本工作的目录路径
os.chdir("dirname") 改变当前脚本工作目录；相当于shell下cd
os.curdir 返回当前目录: ('.')
os.pardir 获取当前目录的父目录字符串名：('..')
os.makedirs('dirname1/dirname2') 可生成多层递归目录
os.removedirs('dirname1') 若目录为空，则删除，并递归到上一级目录，如若也为空，则删除，依此类推
os.mkdir('dirname') 生成单级目录；相当于shell中mkdir dirname
os.rmdir('dirname') 删除单级空目录，若目录不为空则无法删除，报错；相当于shell中rmdir dirname
os.listdir('dirname') 列出指定目录下的所有文件和子目录，包括隐藏文件，并以列表方式打印
os.remove() 删除一个文件
os.rename("oldname","newname") 重命名文件/目录
os.stat('path/filename') 获取文件/目录信息
os.sep 输出操作系统特定的路径分隔符，win下为"\\",Linux下为"/"
os.linesep 输出当前平台使用的行终止符，win下为"\t\n",Linux下为"\n"
os.pathsep 输出用于分割文件路径的字符串
os.name 输出字符串指示当前使用平台。win->'nt'; Linux->'posix'
os.system("bash command") 运行shell命令，直接显示
os.environ 获取系统环境变量
os.path.abspath(path) 返回path规范化的绝对路径
os.path.split(path) 将path分割成目录和文件名二元组返回
os.path.dirname(path) 返回path的目录。其实就是os.path.split(path)的第一个元素
os.path.basename(path) 返回path最后的文件名。如何path以／或\结尾，那么就会返回空值。即os.path.split(path)的第二个元素
os.path.exists(path) 如果path存在，返回True；如果path不存在，返回False
os.path.isabs(path) 如果path是绝对路径，返回True
os.path.isfile(path) 如果path是一个存在的文件，返回True。否则返回False
os.path.isdir(path) 如果path是一个存在的目录，则返回True。否则返回False
os.path.join(path1[, path2[, ...]]) 将多个路径组合后返回，第一个绝对路径之前的参数将被忽略
os.path.getatime(path) 返回path所指向的文件或者目录的最后存取时间
os.path.getmtime(path) 返回path所指向的文件或者目录的最后修改时间eighth:Decorative device
def foo():
print 'foo'
def foo():
print 'before do something'
print 'foo'
print 'after'
def foo():
print 'foo'
def wrapper(func):
print 'before'
func()
print 'after'
wrapper(foo)
def foo():
print 'foo'
def wrapper(func):
def result():
print 'before'
func()
print 'after'
return result
Do = wrapper(foo)
Do()
'''
def wrapper(func):
def result():
print 'before'
func()
print 'after'
return result
@wrapper
def foo():
print 'foo'
foo()#!/usr/bin/env python
#coding:utf-8
def Before(request,kargs):
print 'before'
def After(request,kargs):
print 'after'
def Filter(before_func,after_func):
def outer(main_func):
def wrapper(request,kargs):
before_result = before_func(request,kargs)
if(before_result != None):
return before_result;
main_result = main_func(request,kargs)
if(main_result != None):
return main_result;
after_result = after_func(request,kargs)
if(after_result != None):
return after_result;
return wrapper
return outer
@Filter(Before, After)
def Index(request,kargs):
print 'index'
if __name__ == '__main__':
Index(1,2)
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