4-array/heapq/queue模块

港控/mmm° 2022-03-02 03:58 208阅读 0赞

# array #

array 定义了一个非常类似list的模块，其array 函数接受两个参数，第一个参数是预先定义好的类型，第二个参数，一般为一个序列。 很少见到  
代码：

import array
    
    a = array.array('b',b'abcd')
    print(a)
    print(a[0])

输出：

array('b', [97, 98, 99, 100])
    97

# heapq #

heapq 是python中实现堆排序的模块。

from heapq import *
    import random
    # 创建一个堆排序
    data = []
    for i in range(10):
        heappush(data,random.randint(1,20))
    
    print(data)
    
    # 使用 heappop 移除最小的元素
    small_num = heappop(data)
    print(small_num)
    print('pop移除最小元素后: ',data)
    # 使用heapreplace替换最小元素，会先执行pop，然后replace
    n = heapreplace(data,100)
    print(n)
    print('执行replace后:',data)
    
    # n个最大 / n个最小
    lagest = nlargest(3,data)
    small = nsmallest(3,data)
    
    print("3个最大的值：",lagest)
    print("3个最小的值：",small)

输出

[2, 3, 8, 7, 4, 18, 12, 17, 16, 13]
    2
    pop移除最小元素后:  [3, 4, 8, 7, 13, 18, 12, 17, 16]
    3
    执行replace后: [4, 7, 8, 16, 13, 18, 12, 17, 100]
    3个最大的值： [100, 18, 17]
    3个最小的值： [4, 7, 8]

# queue #

队列，在线程一节有总结过，有先进先出队列，也有优先级队列，队列结合线程，可以保证线程之间通信的安全。这里主要看一下优先级队列

from queue import PriorityQueue
    import threading
    import functools
    Q = PriorityQueue()
    
    @functools.total_ordering
    class Job:
        def __init__(self,priority,desc):
            self.priority = priority
            self.desc = desc
            return 
        # 定义优先级比较
        def __eq__(self,other):
            try:
                self.priority == other.priority
            except AttributeError as e:
                return NotImplemented
        
        def __lt__(self,other):
            try:
                self.priority < other.priority
            except AssertionError:
                return NotImplemented
    
    def worker():
        while not Q.empty():
            item = Q.get()
            import time 
            time.sleep(1)
            print(item.desc)
        
        Q.all_tasks_done
    
    
    if __name__ == "__main__":
        Q.put(Job(3,"mid job"))
        Q.put(Job(10,"important job"))
        Q.put(Job(1,"low job"))
        ts = [threading.Thread(target=worker),threading.Thread(target=worker)]
        for t in ts:
            t.start()
        
        t.join()

输出

important job
    mid job
    low job