补充 collections 模块

# collections 模块
# from  collections import  namedtuple
# P= namedtuple('Point',["x",'y'])
# p=P(1,2)
# print(p.x)
# print(p.y)
# 队列：先进先出

# deque 双端队列
# from  collections import deque
# q = deque(['a','b','c'])
# q.append('x')
# q.appendleft('y')
# print(q)
# print(q.pop())
# print(q.pop()) #从右边依次取值
# print(q.popleft())#依次从左边取值
# print(q.popleft())

# OrderedDict
# from  collections import  OrderedDict
# d=dict([('a',1),('b',2),('c',3)])
# #d  此刻dict的Key是无序的
# d=OrderedDict([('a',1),('b',2),('c',3)])
# #此刻 d的Keyshi 有序的
# for key in d:
#     print(key)

# defaultdict  下面先举例子来展示它的应用可以减少代码

# 有如下列表[11,22,33,44,55,66,77,88,99] 将所有大于66的值保存在
# 字典的第一个Key中，将所有大于66的值保存至第二个Key中。
# 首先我们看一下原来没有 defaultdict 时候的代码
# values = [11,22,33,44,55,66,77,88,99,90]
# my_dict={}
# for value in values:
#     if value>66:
#         if my_dict['k1']:
#             my_dict['k1'].append(value)
#         else:
#             my_dict['k1']=[value]
#     else:
#         if my_dict['k2']:
#             my_dict['k2'].append(value)
#         else:
#             my_dict['k2']=[value]
# print(my_dict)
# 应用了  defaultdict 代码明显降低
# from  collections import  defaultdict
# values = [11,22,33,44,55,66,77,88,99,90]
#
# my_dict=defaultdict(list)
# for value in values:
#     if value >66:
#         my_dict['k1'].append(value)
#     else:
#         my_dict['k2'].append(value)
# print(my_dict)

# Counter
# from  collections import  Counter
# c= Counter('abcdeabcdabcdba')
# print(c)#查看字符串中各个字母中出现的次数Counter({'a': 4, 'b': 4, 'c': 3, 'd': 3, 'e': 1})