python 内建函数

  abs(): 绝对值
  max(): 最大值
  min(): 最小值

  len():    序列(字符串、元组和列表)的长度

  divmod(): 两个数的商和余数

>>> divmod(5,2)
(2, 1)
>>> divmod(2,5)
(0, 2)

  pow():    幂次操作

  round():  转换为有一定精度的小数

  callable():   测试某个函数是否可被调用

>>> min(1,2,3)
1
>>> callable(min)
True
>>> callable(f)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'f' is not defined
>>> 
>>> 
>>> f=100
>>> 
>>> callable(f)
False
>>> def f():
...     pass
... 
>>> callable(f)
True

  isinstance(): 判断类型，eg:isinstance(l,list)

>>> l
[1, 2, 3, 4, 6]
>>> type(l)
<type 'list'>
>>> type([])
<type 'list'>
>>> if type([])==type([]):
... print 'ok'
  File "<stdin>", line 2
    print 'ok'
        ^
IndentationError: expected an indented block
>>> if type(l)==type([]):
...     print 'ok'
... 
ok
>>> isinstance(l,list)
True

  cmp():        比较两个字符串是否一样

>>> cmp("hello","hello")
0

  range():      返回一个生成好的序列

  xrange():     返回一个序列对象，生存器

  type():查看类型

  int(),long(),float()和complex()数据类型转换

  str(),list(),tuple(),hex(),oct(),chr()和ord()均为类型转化函数

  python String函数

  str.capitalize():把字符串首字母变为大写

>>> str.capitalize(s)
'Hello world'
>>> s.capitalize()
'Hello world'
>>> s
'hello world'
>>> s.replace("hello",'good')
'good world'
>>> s
'hello world'
>>> help(str.replace)

  str.replace():替换字符串中的字母

>>> s
'hello world'
>>> s.replace("hello",'good')
'good world'
>>> s
'hello world'
>>> help(str.replace)

>>> ss="123123123"
>>> ss.replace('1','x')
'x23x23x23'
>>> ss.replace('1','x',1)
'x23123123'
>>> ss.replace('1','x',2)
'x23x23123'
>>> ss.replace('1','x',3)
'x23x23x23'

  str.split():字符串切割

>>> ip="192.168.1.255"
>>> ip
'192.168.1.255'
>>> ip.split('.')
['192', '168', '1', '255']
>>> ip.split('.',1)
['192', '168.1.255']
>>> ip.split('.',2)
['192', '168', '1.255']
>>> ip.split('.',3)
['192', '168', '1', '255']
>>>

序列处理函数：

len():返回序列的长度

max():返回序列的最大值

min():返回序列的最小值

其他：

filter():函数对序列进行操作，有效时保持序列值不变。

>>> def f(x):
...     if x>5:
...             return True
... 
>>> f(10)
True
>>> l = range(10)
>>> l
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> filter(f,l)
[6, 7, 8, 9]
>>>

zip():

>>> name = ['tianzhaixing','wang','tom']
>>> age = [26,24,30]
>>> tel = ['158','135','180']
>>> 
>>> zip(name,age,tel)
[('tianzhaixing', 26, '158'), ('wang', 24, '135'), ('tom', 30, '180')]
>>>

map():

>>> name = ['tianzhaixing','wang','tom']
>>> age = [26,24,30]
>>> tel = ['158','135','180']
>>> map(None,name,age,tel)
[('tianzhaixing', 26, '158'), ('wang', 24, '135'), ('tom', 30, '180')]
>>>

>>> a = [1,3,5]
>>> b = [2,4,6]
>>> def mf(x,y):
...     return x*y
... 
>>> map(None,a,b)
[(1, 2), (3, 4), (5, 6)]
>>> map(mf,a,b)
[2, 12, 30]
>>> 

>>> foo=range(10)
>>> foo
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> print [x*2+10 for x in foo]
[10, 12, 14, 16, 18, 20, 22, 24, 26, 28]
>>>

zip和map的一点区别：

>>> name
['tianzhaixing', 'wang', 'tom']
>>> age
[26, 24, 30]
>>> tel
['158', '135', '180']
>>> test=[1,2]
>>> zip(name,age,tel)
[('tianzhaixing', 26, '158'), ('wang', 24, '135'), ('tom', 30, '180')]
>>> zip(name,age,tel,test)
[('tianzhaixing', 26, '158', 1), ('wang', 24, '135', 2)]
>>> map(None,name,age,tel,test)
[('tianzhaixing', 26, '158', 1), ('wang', 24, '135', 2), ('tom', 30, '180', None)]
>>>

reduce():递归使用的内建函数

>>> l
[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100]
>>> 
>>> def rf(x,y):
...     return x+y
... 
>>> reduce(rf,l)
5050
>>> help(reduce)

>>> reduce(lambda x,y:x+y,l)
5050


>>> l
[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100]
>>> filter(lambda x:x%2==0,l)
[2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100]
>>> 


>>> foo=range(10)
>>> foo
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> print [x*2+10 for x in foo]
[10, 12, 14, 16, 18, 20, 22, 24, 26, 28]
>>> print [x for x in foo if x % 3 == 0]
[0, 3, 6, 9]
>>>