python基础

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##########python基础###########
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如何运行python程序

#####交互式#####
whwu@master:~/script/python> python
Python 2.6.6 (r266:84292, Jul 23 2015, 15:22:56)
[GCC 4.4.7 20120313 (Red Hat 4.4.7-11)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> print 'Hello World!'
Hello World!
>>>
Ctrl-D 退出

#####运行模块文件#####
whwu@master:~/script/python/example> cat spam.py
import sys
print sys.argv
whwu@master:~/script/python/example> python spam.py -i eggs
['spam.py', '-i', 'eggs']


#####Unix脚本#####
whwu@master:~/script/python/example> cat charpter1_exam1.py
#!/usr/bin/env python

print 'the bright side of life.'
whwu@master:~/script/python/example> ./charpter1_exam1.py
the bright side of life.



#####模块文件基础#####
whwu@master:~/script/python/example> cat myfile.py
title="The Meaning of Life"
whwu@master:~/script/python/example> python
Python 2.6.6 (r266:84292, Jul 23 2015, 15:22:56)
[GCC 4.4.7 20120313 (Red Hat 4.4.7-11)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import myfile              #python寻找文件时，它知道应该包括后缀                                            
>>> print myfile.title
The Meaning of Life
>>>
KeyboardInterrupt
>>>

whwu@master:~/script/python/example> cat charpter1_exam2.py
#!/usr/bin/env python

import myfile
print myfile.title
whwu@master:~/script/python/example> ./charpter1_exam2.py
The Meaning of Life




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##########python类型与操作符###########
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#####数字#####
按位运算符是把数字看作二进制来进行计算的。Python中的按位运算法则如下：

 
按位运算符
whwu@master:~/script/python/example> python
Python 2.6.6 (r266:84292, Jul 23 2015, 15:22:56)
[GCC 4.4.7 20120313 (Red Hat 4.4.7-11)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> 5&3		#按位与   101  11 相同位仅为个位1 ，故结果为 1
1
>>> 5|3         #按位或   |  举例： 5|3 = 7  解释： 101  11 出现1的位是 1 1 1，故结果为 111
7
>>> 5^3		#按位异或  解释： 101  11 对位相加(不进位)是 1 1 0，故结果为 110
6
>>> ~5		#按位反转 解释： 将二进制数+1之后乘以-1，即~x = -(x+1)，-(101 + 1) = -110
-6
>>> 5<<2        #按位左移   解释：101 向左移动2位得到 10100 ，即右面多出2位用0补
20
>>> 5>>2	#按位右移 解释：101 向右移动2位得到 1，即去掉右面的2位
1


>>> import math  #应用库函数
>>> pi
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'pi' is not defined
>>> math pi
  File "<stdin>", line 1
    math pi
          ^
SyntaxError: invalid syntax
>>> math.pi
3.1415926535897931
>>> abs(-42)
42
>>> 2**4
16

#####字符串####

基本操作
>>> len('avd')
3
>>> 'as'+'234'+'edc'
'as234edc'
>>> 'HaHa!'*4
'HaHa!HaHa!HaHa!HaHa!'



>>> myjob='hacker'
>>> for c in myjob:print c   #迭代
...
h
a
c
k
e
r
>>> 'k' in myjob     #成员关系
True


>>> s='spam'   #索引和分片
>>> s[0],s[-1]
('s', 'm')
>>> s[1:3]
'pa'
>>> s[1:]
'pam'
>>> s[-1:]
'm'
>>> s[:-1]
'spa'


>>> s    #修改与格式化
'spam!'
>>> s=s[:4]+'Burger'+s[-1]
>>> s
'spamBurger!'
>>> 'That is %d %s bird!'% (1,'dead' )
'That is 1 dead bird!'

>>> exclamation = "Ni"
>>> "The knights who say %s!" % exclamation
'The knights who say Ni!'
>>> "%d %s %d you" % (1, 'spam', 4)
'1 spam 4 you'
>>> "%s -- %s -- %s" % (42, 3.14159, [1, 2, 3])
'42 -- 3.14159 -- [1, 2, 3]'


###字符串工具###
>>> import string   # 标准模块
>>> S="spammify"
>>> string.upper(S) #转化为大写
'SPAMMIFY'
>>> string.find(S,"mm") #返回索引的子串
3
>>> string.atoi("42"),`42`  #转化字符串
(42, '42')
>>> string.atoi("42")+1   # 转化为数字
43
>>> "spam"+`42`  # 反引号是字符串
'spam42'


###字符串常量变量###
>>> mixed="Guido's"   # 单引号在双引号中
>>> mixed
"Guido's"
>>> mixed='Guido"s'   # 双引号在单引号中
>>> mixed
'Guido"s'
>>> mixed='Guido\'s'  # 反斜线转译符
>>> mixed
"Guido's"

>>> split="This" "is" "concatenated" #合并邻近的字符串常量
>>> split
'Thisisconcatenated'
>>> split="This" " is " "concatenated"
>>> split
'This is concatenated'



####内置模块sys的argv属性####
whwu@master:~/script/python/example> cat echo.py
import sys
print sys.argv[1:]
whwu@master:~/script/python/example> python echo.py -a -b -c
['-a', '-b', '-c']

whwu@master:~/script/python/example> cat echo.py
import sys
print sys.argv
whwu@master:~/script/python/example> python echo.py -a -b -c
['echo.py', '-a', '-b', '-c']



####列表####

基本操作
>>> len([1,2,3])	# 长度
3
>>> [1,2,3]+[4,5,6]	#合并
[1, 2, 3, 4, 5, 6]
>>> ['Ni!']*4		#重复
['Ni!', 'Ni!', 'Ni!', 'Ni!']

>>> for x in [1,2,3]:print x,	#迭代
...
1 2 3


索引和分片
>>> L=['apple','banana','canada','dog']  
>>> L
['apple', 'banana', 'canada', 'dog']
>>> L[2]	#从0开始的偏移
'canada'
>>>
>>> L[-1]       #负偏移：从右数起
'dog'
>>> L[1:]       #分片取得片段
['banana', 'canada', 'dog']



原位改变列表
>>> L=['apple','banana','cat','dog']
>>> L[1]
'banana'
>>> L
['apple', 'banana', 'cat', 'dog']
>>> L[1]='BANANA'	#索引赋值
>>> L
['apple', 'BANANA', 'cat', 'dog']
>>> L[0:2]=['eat','more']	#分片赋值：删除0,1并插入
>>> L
['eat', 'more', 'cat', 'dog']
>>> L[1:2]=['AB','BC']		#删除1，插入两项
>>> L
['eat', 'AB', 'BC', 'cat', 'dog']

>>> L.append('eat')	# append方法调用
>>> L
['eat', 'AB', 'BC', 'cat', 'dog', 'eat']
>>> L.sort()		# 排序列表项
>>> L
['AB', 'BC', 'cat', 'dog', 'eat', 'eat']


>>> L
['AB', 'BC', 'cat', 'dog', 'eat', 'eat']
>>>
>>>
>>> del L[-1]	#删除最后一项
>>> L
['AB', 'BC', 'cat', 'dog', 'eat']
>>> del L[1:]	#删除1之后的项
>>> L
['AB']


字典
>>> d2={'spam':2,'ham':1,'eggs':3} #建立字典
>>> d2['spam']	#用键取值
2
>>> len(d2)	#字典中的项数
3
>>> d2.has_key('ham')	#键成员关系测试
True
>>> d2.keys()    #键的列表
['eggs', 'ham', 'spam']



----比较、相等性和真值----
>>> L1=[1,('a',3)]	# 同样的值，唯一的对象
>>> L2=[1,('a',3)]
>>> L1==L2	# ==操作符测试值是否相等，python运行了一个相等测试，递归比较所有的内嵌对象
True
>>> L1 is L2	# is操作符测试它们是否真的是同一个对象
False


----同层深度的重复加----
>>> L=[4,5,6]
>>> X=L*4
>>> Y=[L]*4
>>> Z=L[:]*4
>>> Z=[L[:]]*4	# 一份嵌入的L的拷贝
>>> X
[4, 5, 6, 4, 5, 6, 4, 5, 6, 4, 5, 6]
>>> Y
[[4, 5, 6], [4, 5, 6], [4, 5, 6], [4, 5, 6]]
>>> Z
[[4, 5, 6], [4, 5, 6], [4, 5, 6], [4, 5, 6]]
>>> L[1]=0
>>> X
[4, 5, 6, 4, 5, 6, 4, 5, 6, 4, 5, 6]
>>> Y
[[4, 0, 6], [4, 0, 6], [4, 0, 6], [4, 0, 6]]
>>> Z
[[4, 5, 6], [4, 5, 6], [4, 5, 6], [4, 5, 6]]


类型类别复习

对象类型	种类		可变
数字		数字的		不
列表		序列的		可
字符串		序列的		不
字典		映射的		可
元祖		序列的		不
文件		扩展程序	-

>>> T=(1,2,3)
>>> T[2]=4  #error 元组不可原位改变
>>> T=T[:2]+(4,)
>>> T
(1, 2, 4)