python 堆和优先队列的使用详解

import heapq
#向堆中插入元素，heapq会维护列表heap中的元素保持堆的性质
heapq.heappush(heap, item)
#heapq把列表x转换成堆
heapq.heapify(x)
#从可迭代的迭代器中返回最大的n个数，可以指定比较的key
heapq.nlargest(n, iterable[, key])
#从可迭代的迭代器中返回最小的n个数，可以指定比较的key
heapq.nsmallest(n, iterable[, key])
#从堆中删除元素，返回值是堆中最小或者最大的元素
heapq.heappop(heap)

def heapq_int():
  heap = []
  #以堆的形式插入堆
  heapq.heappush(heap,10)
  heapq.heappush(heap,1)
  heapq.heappush(heap,10/2)
  [heapq.heappush(heap,i) for i in range(10)]
  [heapq.heappush(heap,10 - i) for i in range(10)]
  #最大的10个元素
  print heapq.nlargest(10,heap)
  #输出所有元素
  print [heapq.heappop(heap) for i in range(len(heap))]

def heapq_tuple():
  heap = []
  #向推中插入元组
  heapq.heappush(heap,(10,'ten'))
  heapq.heappush(heap,(1,'one'))
  heapq.heappush(heap,(10/2,'five'))
  while heap:
    print heapq.heappop(heap),
  print

class Skill(object):
  def __init__(self,priority,description):
    self.priority = priority
    self.description = description
  def __lt__(self,other):#operator < 
    return self.priority < other.priority
  def __ge__(self,other):#oprator >=
    return self.priority >= other.priority
  def __le__(self,other):#oprator <=
    return self.priority <= other.priority
  def __cmp__(self,other):
    #call global(builtin) function cmp for int
    return cmp(self.priority,other.priority)
  def __str__(self):
    return '(' + str(self.priority)+',\'' + self.description + '\')'

def heapq_class():
  heap = []
  heapq.heappush(heap,Skill(5,'proficient'))
  heapq.heappush(heap,Skill(10,'expert'))
  heapq.heappush(heap,Skill(1,'novice'))
  while heap:
    print heapq.heappop(heap),
  print 

#向队列中添加元素
Queue.put(item[, block[, timeout]])
#从队列中获取元素
Queue.get([block[, timeout]])
#队列判空
Queue.empty()
#队列大小
Queue.qsize()

try:
  import Queue as Q #python version < 3.0
except ImportError:
  import queue as Q #python3.*
def PriorityQueue_int():
  que = Q.PriorityQueue()
  que.put(10)
  que.put(1)
  que.put(5)
  while not que.empty():
    print que.get(),
  print

def PriorityQueue_tuple():
  que = Q.PriorityQueue()
  que.put((10,'ten'))
  que.put((1,'one'))
  que.put((10/2,'five'))
  while not que.empty():
    print que.get(),
  print

class Skill(object):
  def __init__(self,priority,description):
    self.priority = priority
    self.description = description
  #下面两个方法重写一个就可以了
  def __lt__(self,other):#operator < 
    return self.priority < other.priority
  def __cmp__(self,other):
    #call global(builtin) function cmp for int
    return cmp(self.priority,other.priority)
  def __str__(self):
    return '(' + str(self.priority)+',\'' + self.description + '\')'

def PriorityQueue_class():
  que = Q.PriorityQueue()
  skill5 = Skill(5,'proficient')
  skill6 = Skill(6,'proficient6')
  que.put(skill6)
  que.put(Skill(5,'proficient'))
  que.put(Skill(10,'expert'))
  que.put(Skill(1,'novice'))
  while not que.empty():
    print que.get(),
  print