python模块之collections模块
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2022-04-27 20:52:06
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() 有序字典 OrderedDict (对字典的补充,可以记住字典元素添加的顺序) 默认字典 defaultdict,(指定字典值的类型) 可命名元组 namedtuple (给元组对 ......
计数器 counter
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计数元素迭代器 elements()
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计数对象拷贝 copy()
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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)
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