Day1_collections库学习

# encoding:utf-8
#
""" @version:1.0
    @author Heng
    @time: 6/24/2016 4:52 PM
    
"""

'''
    collections 是python内建的集合模块

    学习一些常用的函数
'''
# namedtuple  用于创建一个自定义的tuple对象

from collections import namedtuple

# 定义一个2维坐标
Point = namedtuple('Point', ['x', 'y'])
p = Point(1, 3)
print p.x, p.y
# result 1 3
# 定义一个圆
# namedtuple('名称', [属性list]):
Circle = namedtuple('circle', ['x', 'y', 'r'])
c = Circle(1, 1, 3)
print c.x, c.y, c.r
# result 1  1 3


# deque 提高插入与删除操作的list,适用于队列和栈

from collections import deque

q = deque(range(10))
q.append('x')
q.appendleft('x1')
print q
# result deque(['x1', 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 'x'])


# defaultdict  与dict一样，解决key 不存在时的情况，返回一个默认值

from collections import defaultdict

dd = defaultdict(lambda: 'key not found')
print dd['key']

# result key not found

# Counter  一个计数器

from collections import Counter

c = Counter()
for char in "my name is niu,what's your name":
    c[char] = c[char] + 1
print c

# result 统计出字符出现的个数
# Counter({' ': 5, 'a': 3, 'm': 3, 'n': 3, 'e': 2, 'i': 2, 's': 2, 'u': 2, 'y': 2, "'": 1, 'h': 1, ',': 1, 'o': 1, 'r': 1, 't': 1, 'w': 1})

# OrderedDict  一个有序的dict功能

from collections import OrderedDict

d = {'a': 1, 'b': 2, 'c': 3, 'd': 4, '': 5}
print d  # result{'a': 1, 'c': 3, 'b': 2, 'e': 5, 'd': 4} 默认dict是无序的集合

b = OrderedDict(d)
print b

#result          {'a': 1, '': 5, 'c': 3, 'b': 2, 'd': 4}
#     OrderedDict([('a', 1), ('', 5), ('c', 3), ('b', 2), ('d', 4)])