读书笔记---Python绝对简明手册(个人认为Python是C++的最佳拍档)

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• PyAbsolutelyZipManual

Python 绝对简明手册 -- [email protected] ::-- ZoomQuiet [2006-09-15 04:35:33]

1. Py2.5 绝对简明手册
   1. 语法
      1. if
      2. for
      3. pass
      4. in
      5. 参数格式 **para
      6. Lambda函数
      7. List的函数
      8. 列表推导式
      9. del
      10. 元组
      11. set
      12. zip
      13. reversed反向循环
      14. sorted排序
      15. sequence比大小
      16. 导入模块
      17. 包
      18. 格式化输出
      19. 等效代码
      20. 读写文件:
      21. pickle
      22. 初识类
          1. 类继承
          2. 多重继承
      23. Iterators 迭代器
      24. 生成器表达式
   2. 常用函数不完全手册
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1. Py2.5 绝对简明手册

简述

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PYthon绝对简明手册,初学必备!

• -- For Python2.5

版本:0.2 beta

作者:张沈鹏

参考:python2.5中文教程 

感谢:Zoom.Quiet limodou

我的技术Blog 我的C++Blog 我的文学Blog

• -- 欢迎指出错误和遗漏,提出建议和意见,请发信到[email protected]

1.1. 语法

1.1.1. if

<script type="text/javascript"> function isnumbered(obj) { return obj.childNodes.length && obj.firstChild.childNodes.length && obj.firstChild.firstChild.className == 'LineNumber'; } function nformat(num,chrs,add) { var nlen = Math.max(0,chrs-(''+num).length), res = ''; while (nlen>0) { res += ' '; nlen-- } return res+num+add; } function addnumber(did, nstart, nstep) { var c = document.getElementById(did), l = c.firstChild, n = 1; if (!isnumbered(c)) if (typeof nstart == 'undefined') nstart = 1; if (typeof nstep == 'undefined') nstep = 1; n = nstart; while (l != null) { if (l.tagName == 'SPAN') { var s = document.createElement('SPAN'); s.className = 'LineNumber' s.appendChild(document.createTextNode(nformat(n,4,' '))); n += nstep; if (l.childNodes.length) l.insertBefore(s, l.firstChild) else l.appendChild(s) } l = l.nextSibling; } return false; } function remnumber(did) { var c = document.getElementById(did), l = c.firstChild; if (isnumbered(c)) while (l != null) { if (l.tagName == 'SPAN' && l.firstChild.className == 'LineNumber') l.removeChild(l.firstChild); l = l.nextSibling; } return false; } function togglenumber(did, nstart, nstep) { var c = document.getElementById(did); if (isnumbered(c)) { remnumber(did); } else { addnumber(did,nstart,nstep); } return false; } </script> <script type="text/javascript"> document.write(' Toggle line numbers<\/a>'); </script> Toggle line numbers

 1 x=int(raw_input("Please enter an integer:"))
 2 if x<0:
 3     print 'Negative Number'
 4 elif x==0:
 5     print 'Zero'
 6 else:
 7     print 'Positive Number'

1.1.2. for

<script type="text/javascript"> document.write(' Toggle line numbers<\/a>'); </script> Toggle line numbers

 1 a=['cat','door','example']
 2 for x in a:
 3     print x

#如果要修改a的内容，则用a的副本循环，如：

for x in a[:] : 
    ..................... 

<script type="text/javascript"> document.write(' Toggle line numbers<\/a>'); </script> Toggle line numbers

 1 >>>range(10,0,-3)
 2 [10,7,4,1]
 3 a=['cat','door','example']
 4 for i in range(len(a)):
 5     print i,a[i]

break,continue 用法和C＋＋中类似

1.1.3. pass

while True: 
    pass #忽略，什么也不做 

<script type="text/javascript"> document.write(' Toggle line numbers<\/a>'); </script> Toggle line numbers

 1 def fib(n=1000):#参数可以有默认值，多个可选参数赋值可以直接写"参数变量名＝值"来快速赋值 
 2     """这里给函数写文档注释"""
 3     a,b=0,1
 4     while b<n:
 5        print b
 6        a,b=b,a+b

#函数可以重命名,如

<script type="text/javascript"> document.write(' Toggle line numbers<\/a>'); </script> Toggle line numbers

 1 f=fib
 2 f(223)

1.1.4. in

• <script type="text/javascript"> document.write(' Toggle line numbers<\/a>'); </script> Toggle line numbers

   1 if 'yes' in  ('y','ye','yes'):print  'ok'
  

1.1.5. 参数格式 **para

#参数格式为 **para 表示接受一个字典,为 *para 表示接受一个元组

<script type="text/javascript"> document.write(' Toggle line numbers<\/a>'); </script> Toggle line numbers

 1 def test(para1,*args,**dic):
 2     print para1
 3     for arg in args : print arg
 4     keys=dic.keys()
 5     keys.sort()
 6     for key in keys:print key ,':',dic[key]

1.1.6. Lambda函数

• <script type="text/javascript"> document.write(' Toggle line numbers<\/a>'); </script> Toggle line numbers

   1 def make_incrementor(n):
   2     return lambda x: x+n
   3 f=make_incrementor(n)
   4 >>>f(0)
   5 42
   6 >>>f(1)
   7 43
  

1.1.7. List的函数

append(x)    追加到链尾 
extend(L)    追加一个列表 
insert(i,x)   在位置i插入x 
remove(x)   删除第一个值为x的元素,如果不存在会抛出异常 
pop([i])   返回并删除位置为i的元素,i未给定时默认作用在最后一个元素.[i]表示i为可选的 
index(x)    返回第一个值为x的元素,不存在则抛出异常 
count(x)   返回x出现的次数 
sort()   排序 
reverse()   翻转,反转 

filter(function函数 , sequence序列)  返回sequence中使filer为true的

map(function,sequence,[sequence...])  返回新的sequence,序列中值为对每个元素分别调用function.

reduce(function,sequence,[init])  返回一个单值为,计算步骤为 :

• 第1个结果=function(sequence[0],sequence[1])
• 第2个结果=function(第1个结果,sequence[2])
• 返回最后一个计算得值
• 如果有init,则先调用

function(init,sequence[0])  sequence只有一个元素时,返回该元素,为空时抛出异常.

1.1.8. 列表推导式

freshfruit=['  banana  ','   loganberry  '] 
>>>[weapon.strip() for weapon in freshfruit] 
['banana','loganberry'] 
vec=[2,4,6] 
>>>[3*x for x in vec if x>3] 
[12,18] 
>>>[(x,x**2) for x in vec]    #一个元素一定要是一个sequence,而
[x,x**2 for x in vec]是错误的 
[(2,4),(4,16),(6,36)] 
vec2=[4,3,-9] 
[x*y for x in vec for y in vec2] 
[vec[i]+vec2[i] for i in range(len(vec))] 
[str(round(355/113.0,i)) for i in range(1,6)] #str()是转换类型为可以打印的字符

1.1.9. del

<script type="text/javascript"> document.write(' Toggle line numbers<\/a>'); </script> Toggle line numbers

 1 a=[1,2,3,4,5,6]
 2 del a[0]
 3 >>>a
 4 [2,3,4,5,6]
 5 del a[2:4]
 6 >>>a
 7 [2,3,6]
 8 del a[:]
 9 >>>a
 10 []
 11 del a
 12 >>>a

抛出异常

1.1.10. 元组

t=1234,5567,'hello' 
x,y,z=t    #拆分操作可以应用于所有sequence 
>>>x 
1234 
u=t,(1,2,3) 
>>>u 
((1234,5567,'hello'),(1,2,3)) 
empty=() #空元组 
singleton='hi', #单个元素的元组 

1.1.11. set

set（集合）：无序不重复的元素集

<script type="text/javascript"> document.write(' Toggle line numbers<\/a>'); </script> Toggle line numbers

 1 basket = ['apple','orange','apple','pear','apple','banana']
 2 fruit=set(basket)
 3 >>>fruit
 4 set(['orange', 'pear', 'apple', 'banana'])
 5 >>>'orange' in fruit
 6 True
 7 a=set('abracadabew')
 8 >>>a
 9 set(['a', 'c', 'b', 'e', 'd', 'r', 'w'])
 10 b=set('wajgwaoihwb')
 11 >>> b
 12 set(['a', 'b', 'g', 'i', 'h', 'j', 'o', 'w'])
 13 >>> a-b    #差 
 14 set(['c', 'r', 'e', 'd'])
 15 >>> a|b   #并 
 16 set(['a', 'c', 'b', 'e', 'd', 'g', 'i', 'h', 'j', 'o', 'r', 'w'])
 17 >>> a&b   #交 
 18 set(['a', 'b', 'w'])
 19 >>>a^b   #(并-交) 
 20 set(['c', 'e', 'd', 'g', 'i', 'h', 'j', 'o', 'r'])

=== dict ===

字典:关键字为不可变类型,如字符串,整数,只包含不可变对象的元组.列表等不可以作为关键字.如果列表中存在关键字对,可以用dict()直接构造字典.而这样的列表对通常是由列表推导式生成的.

<script type="text/javascript"> document.write(' Toggle line numbers<\/a>'); </script> Toggle line numbers

 1 tel={'jack':4098,'sape':4139}
 2 tel['guido']=4127
 3 >>> tel
 4 {'sape': 4139, 'jack': 4098, 'guido': 4127}
 5 >>>tel['jack']
 6 4098
 7 del tel['sape']
 8 >>>tel.keys()
 9 ['jack', 'guido']
 10 >>>tel.has_key('jack')
 11 True
 12 knight={'gallahad':'the pure','robin':'the brave'}
 13 for k,v in knight.iteritems():
 14     print k,v

输出:

<script type="text/javascript"> document.write(' Toggle line numbers<\/a>'); </script> Toggle line numbers

 1 gallahad the pure
 2 robin the brave

enumerate()返回索引位置和对应的值

<script type="text/javascript"> document.write(' Toggle line numbers<\/a>'); </script> Toggle line numbers

 1 for i,v in enumerate(['tic','tac','toe'])
 2     print i,v

输出: 0 tic

1 tac

2 toe

1.1.12. zip

zip用于多个sequence的循环

<script type="text/javascript"> document.write(' Toggle line numbers<\/a>'); </script> Toggle line numbers

 1 questions=['name','quest','favorite color']
 2 answers=['lancelot','the holy grail','blue']
 3 for q,a in zip(questions,answers):
 4     print 'What is your %s ? It is %s.'%(q,a)

输出:

What is your name ? It is lancelot. 
What is your quest ? It is the holy grail. 
What is your favorite color ? It is blue. 

1.1.13. reversed反向循环

<script type="text/javascript"> document.write(' Toggle line numbers<\/a>'); </script> Toggle line numbers

 1 for i in reversed(range(1,4)):
 2     print i

输出:

3 
2