计数器 Counter
-
计数元素迭代器 elements()
-
计数对象拷贝 copy()
-
计数对象清空 clear（）
from collections import Counter
#import collections
d = Counter("abdadakdabfdj") #对值计数，返回一个对象
print(d, type(d)) #Counter({'a': 4, 'd': 4, 'b': 2, 'k': 1, 'f': 1, 'j': 1}) <class 'collections.Counter'>
print(list(d), type(d)) #['a', 'b', 'd', 'k', 'f', 'j'] <class 'collections.Counter'>
print(dict(d), type(d)) #{'a': 4, 'b': 2, 'd': 4, 'k': 1, 'f': 1, 'j': 1} <class 'collections.Counter'>
print(d.elements()) #elements()方法返回一个迭代器，内容为进行计数的元素
for i in d.elements():
print(i) # a a a a d d d d b b k f j
d1 = d.copy()
print(d1,type(d1)) #Counter({'a': 4, 'd': 4, 'b': 2, 'k': 1, 'f': 1, 'j': 1}) <class 'collections.Counter'>
d2 = d.subtract("aaa")
print(d2,type(d2))
d3 = d.update('aaa')
print(d3,type(d3))
d4 = d.pop("j")
print(d4,d) # 1 Counter({'a': 4, 'd': 4, 'b': 2, 'k': 1, 'f': 1})
d.clear() # clear()方法清空计数的元素\
print(d) # Counter()
有序字典 OrderedDict (对字典的补充，可以记住字典元素添加的顺序)
from collections import OrderedDict
order_dict = OrderedDict()
print(order_dict,type(order_dict))
order_dict["c"] = 94
order_dict["b"] = 92
order_dict["d"] = 95
order_dict["a"] = 90
print(order_dict,type(order_dict)) #返回有序字典对象，OrderedDict([('c', 94), ('b', 92), ('d', 95), ('a', 90)]) <class 'collections.OrderedDict'>
print(dict(order_dict),type(order_dict))#{'c': 94, 'b': 92, 'd': 95, 'a': 90} <class 'collections.OrderedDict'>
print(list(order_dict),type(order_dict))#['c', 'b', 'd', 'a'] <class 'collections.OrderedDict'>
print(order_dict.popitem()) #提取出字典的最后一个键值对 ('a', 90)
print(order_dict) #OrderedDict([('c', 94), ('b', 92), ('d', 95)])
print(order_dict.pop("b")) #提取出字典指定键对应的值
print(order_dict) #OrderedDict([('c', 94), ('d', 95)])
order_dict.move_to_end("c") #将指定的键值对移动到最后
print(order_dict) #OrderedDict([('d', 95), ('c', 94)])
默认字典 defaultdict，（指定字典值的类型）
from collections import defaultdict
default_dict = defaultdict(list) # 指定字典的值类型为列表
print(default_dict,type(default_dict)) #defaultdict(<class 'list'>, {}) <class 'collections.defaultdict'>
for i in range(10):
default_dict["a"].append(i)
print(default_dict) #defaultdict(<class 'list'>, {'a': [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]})
可命名元组 namedtuple (给元组对应的值起个对应的名字，相当于字典)
from collections import namedtuple
tuple1 = namedtuple("tuple_name",["name","age","school","adress"])
print(tuple1)
tuple1 = tuple1("xu",20,"jinggangshan","jiangxi")
print(tuple1.name)
