python 内置容器

三、python内置容器

标签： python 容器

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3.1 List

定义 访问 切片操作 嵌套 内置函数

 
 
>>> a = [1,'2', ["abc", 1],34]
>>> print a
[1, '2', ['abc', 1], 34]
>>> for o in a:
...     print o         #必须有tab空格，否则o未定义
... 
1
2
['abc', 1]
34
>>> a =[x for x in range(10)] 
>>> a
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> dir(a)
['__add__', '__class__', '__contains__', '__delattr__', '__delitem__', '__delslice__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getitem__', '__getslice__', '__gt__', '__hash__', '__iadd__', '__imul__', '__init__', '__iter__', '__le__', '__len__', '__lt__', '__mul__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__reversed__', '__rmul__', '__setattr__', '__setitem__', '__setslice__', '__sizeof__', '__str__', '__subclasshook__', 'append', 'count', 'extend', 'index', 'insert', 'pop', 'remove', 'reverse', 'sort']
>>> a.append(10)
>>> print a
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
>>> b=[11,12,13]
>>> a.append(b)
>>> a
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, [11, 12, 13]]
>>> a.extend(b)
>>> print a 
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, [11, 12, 13], 11, 12, 13]

3.2 Tuple

定义 类似list的访问方式 不可变对象 隐式tuple调用 
数据交换 拆封与解封

 
 
>>> a=(1,2,3)
>>> type(a)
<type 'tuple'>
>>> print a
(1, 2, 3)
>>> dir(a)
['__add__', '__class__', '__contains__', '__delattr__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getitem__', '__getnewargs__', '__getslice__', '__gt__', '__hash__', '__init__', '__iter__', '__le__', '__len__', '__lt__', '__mul__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__rmul__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', 'count', 'index']
>>> for o in a:
...     print o
... 
1
2
3
>>> b = [x for x in a]
>>> print b
[1, 2, 3]
>>> b=(x for x in a)   
>>> b
<generator object <genexpr> at 0x7f36f045a870>
>>> b.next()
1
>>> a[1]
2
>>> a[1:2]
(2,)
>>> a[:-1]
(1, 2)
>>> print 'abcd %d and %s\n' %(1,'ssss')  #格式化串
abcd 1 and ssss
>>> a
(1, 2, 3)
>>> b = [x for x in a]     #将a元组转化成数组来操作
>>> print b
[1, 2, 3]
>>> b.append(4)
>>> b
[1, 2, 3, 4]
>>> print b
>>> a = (1,[1,2,3],4)
>>> a
(1, [1, 2, 3], 4)
>>> type(a)
<type 'tuple'>
>>> a[2]=2
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'tuple' object does not support item assignment
>>> a[1].append(2)      #对元组中的数组进行增加操作
>>> a
(1, [1, 2, 3, 2], 4)

3.3 Dict

字典的声明 简单的使用 keys()和values() 排序问题

 
 
>>> a= {"b":1, "d":2}
>>> a
{'b': 1, 'd': 2}
>>> type(a)
<type 'dict'>
>>> dir(a)
['__class__', '__cmp__', '__contains__', '__delattr__', '__delitem__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getitem__', '__gt__', '__hash__', '__init__', '__iter__', '__le__', '__len__', '__lt__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__setitem__', '__sizeof__', '__str__', '__subclasshook__', 'clear', 'copy', 'fromkeys', 'get', 'has_key', 'items', 'iteritems', 'iterkeys', 'itervalues', 'keys', 'pop', 'popitem', 'setdefault', 'update', 'values']
>>> if a.has_key('b'):
...     print a['b']
... 
1
>>> a.has_key('c')
False
>>> for o in a.iteritems():
...     print o
... 
('b', 1)
('d', 2)
>>> for o in a.iteritems():
...     print o[1]          #取a的value值
... 
1
2
>>> b=[x for x in a.iterkeys()]
>>> b
['b', 'd']
>>> type(a.itervalues)
<type 'builtin_function_or_method'>
>>> c = [x for x in a.itervalues()]
>>> c
[1, 2]
>>> a.values()
[1, 2]
>>> a ={"d":3, "b":2, "c":1 } 
>>> help(sorted)
>>> e=sorted(a, key=lambda t:t[0])    #按key值排序
>>> e
['b', 'c', 'd']
>>> a
{'c': 1, 'b': 2, 'd': 3}

3.4 Set

定义方式 set唯一集合 合并功能 类型转换

 
 
>>> a=[1,2,3,4,4,5,5];
>>> b=set(a)      
>>> b
set([1, 2, 3, 4, 5])

3.5 map, reduce, filter

• map

 
 
 >>> a=[1,2,3,4,5]
>>> map(lambda x:x*2, a)
[2, 4, 6, 8, 10]
>>> map(lambda x:x^2, a)    #异或操作
[3, 0, 1, 6, 7]
>>> map(lambda x:x*x, a) 
[1, 4, 9, 16, 25]

• reduce 归并

 
 
>>> reduce(lambda x,y: x+y, a)
15
>>> reduce(lambda x,y: x, a)  
1
>>> reduce(lambda x: x*2, a)    #无法实现归并
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: <lambda>() takes exactly 1 argument (2 given)
>>> reduce(lambda x,y: x*y, a)
120

• filter

 
 
>>> filter(lambda x:x%2, a)  
[1, 3, 5]
>>> filter(lambda x:x%2+1, a)
[1, 2, 3, 4, 5]
>>> filter(lambda x:not x%2, a)     
[2, 4]

3.6 迭代器与生成器，协同和半协同

 
 
>>> import os
>>> b = os.walk('.')
>>> print [o for o in b]      #打印所有的环境变量
>>> b.next()                  #空
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
StopIteration
>>> b=os.walk('.')      
>>> b.next()                  #逐个弹出
>>> type(b)
<type 'generator'>
>>> def fab(m):   
...     a,b=1,1
...     while(a<m):
...             yield a
...             a,b = b,a+b
... 
>>> b = fab(b)
>>> b.next()
1
>>> b.next()
1
>>> b.next()
2
>>> b.next()
3