Python其他數據結構collection模塊-namtuple defaultdict deque Queue Counter OrderDict
nametuple
是tuple擴展子類,命名元組,其實本質上簡單類對象
from collections import namedtuple
info = namedtuple("Info", [‘name‘, ‘age‘, ‘height‘])
# 賦值,是不是有點像面向對象中實例變量方式
info.name = "北門吹雪"
info.age = 18
info.height = 175
# 訪問
print(info.name)
其實本質上和下面方式一樣
class Info: def __init__(self): self.name = None self.age = None self.height = None pass info = Info() # 賦值 info.name = "北門吹雪" info.age = 18 info.height = 175 # 訪問 print(info.name)
相關方法
1. _make 初始化賦值, 必須長度一致
from collections import namedtuple
info = namedtuple("Info", [‘name‘, ‘age‘, ‘height‘])._make(["北門吹雪", 18, 175])
# 訪問
print(info.name)
2. _asdict 將nametuple對象轉換為字典對象,是個有序字典
from collections import namedtuple info = namedtuple("Info", [‘name‘, ‘age‘, ‘height‘])._make(["北門吹雪", 18, 175]) # 訪問 print(info._asdict())
defaultdict
是dict的擴展類,訪問字典的key如果沒有則自動設置默認值,並添加進字典
info = dict()
name = info.setdefault(‘name‘, "北門吹雪")
print(name, info)
from collections import defaultdict
# 默認值必須是可叠代對象
info = defaultdict(lambda: "北門吹雪")
name = info[‘name‘]
print(name, info)
deque
雙端隊列, 操作和list類似
list deque 推薦用來保存相同類似數據
特性: deque是線程安全的,list不是線程安全,多線程編程則使用deque
from collections import deque
names = deque()
names.append("北門吹雪")
names.append("QiNiuYun")
names.insert(0, "今日頭條")
print(names)
Queue
隊列(先進先出),通過 deque實現
核心兩個方法 put get,會堵塞
from queue import Queue
message = Queue()
# 放入數據
message.put("北門吹雪")
# 消費數據
print(message.get())
Counter
對可叠代對象做統計出現個數,直接返回統計結果,是dict的子類
from collections import Counter
from random import randint
numbers = [randint(1, 5) for _ in range(20)]
numbers_count = Counter(numbers)
print(numbers_count)
相關方法
1. update 添加新的數據
from collections import Counter
from random import randint
numbers = [randint(1, 5) for _ in range(20)]
numbers_count = Counter(numbers)
print(numbers_count)
# 添加新的數據
numbers_count.update([randint(1, 10) for _ in range(20)])
print(numbers_count)
2. most_common(N) 輸出出現次數當前最多的前N個元素
from collections import Counter
from random import randint
numbers = [randint(1, 5) for _ in range(20)]
numbers_count = Counter(numbers)
print(numbers_count)
# 添加新的數據
numbers_count.update([randint(1, 10) for _ in range(20)])
print(numbers_count)
# 輸出出現次數當前最多的前3個元素,返回列表
print(numbers_count.most_common(3))
OrderDict
繼承dict, 保持字典添加順序,具有dict所有方法
from collections import OrderedDict
info = OrderedDict()
# 填入數據
info["name"] = "北門吹雪"
info[‘age‘] = 18
info[‘height‘] = 175
print(info)
其他方法
1. popitem 默認刪除最後的key:value,並返回
from collections import OrderedDict
info = OrderedDict()
# 填入數據
info["name"] = "北門吹雪"
info[‘age‘] = 18
info[‘height‘] = 175
# 返回元組形式
print(info.popitem(‘name‘))
2. pop 必須傳入key,刪除key:value,返回value
from collections import OrderedDict
info = OrderedDict()
# 填入數據
info["name"] = "北門吹雪"
info[‘age‘] = 18
info[‘height‘] = 175
# 返回age對應的值
print(info.pop(‘age‘))
3. move_to_end 傳入key,將元素移到最後
from collections import OrderedDict
info = OrderedDict()
# 填入數據
info["name"] = "北門吹雪"
info[‘age‘] = 18
info[‘height‘] = 175
# 移動數據
info.move_to_end(‘age‘)
print(info)
經驗:
1. 這些數據類型基礎還是從list tuple set dict基本數據類型擴展而來,本質上添加了一些特性
Python其他數據結構collection模塊-namtuple defaultdict deque Queue Counter OrderDict