Python的優先權隊列

python的優先權隊列，根據優先權來進行隊列排序，但是注意優先權隊列使用heap實現，而heap不是穩定的排序，所以，想要實現同優先權內部也有序，則需要增加一個計數，表示該優先權的順序。參考以下代碼：

1. #!/usr/bin/python
2. from Queue import Queue
3. from Queue import PriorityQueue
4. a1='a1'
5. a2='a2'
6. a3='a3'
7. a4='a4'
8. a5='a5'
10. b1='b1'
11. b2='b2'
12. b3='b3'
13. b4='b4'
14. b5='b5'
16. q = Queue()
17. pq = PriorityQueue()
18. for i in xrange(5):
19.     p = 5 - i
20.     q.put("a"+str(p))
21.     q.put("b"+str(p))
23.     pq.put((p,"a"+str(p)))
24.     pq.put((p,"b"+str(p)))
26. for i in xrange(5):
27.     p = 5 - i
28.     q.put("a"+str(p)+str(i+5))
29.     q.put("b"+str(p)+str(i+5))
31.     pq.put((p,"a"+str(p)+str(i+5)))
32.     pq.put((p,"b"+str(p)+str(i+5)))
34. size = q.qsize()
35. print "queue item size:%s" %size
36. print "queue items:"
37. for i in xrange(size):
38.     print q.get()
40. size = pq.qsize()
41. print "priority queue item size:%s" %size
42. print "priority queue items:"
43. for i in xrange(size):
44.     print pq.get()
46. #"but priority queue with same priority is not queue, if we want so, do the following:"
47. import itertools
48. count = itertools.count()
49. poq = PriorityQueue()
50. for i in xrange(5):
51.     p = 5 - i
52.     poq.put((p,count.next(),"a"+str(p)))
53.     poq.put((p,count.next(),"b"+str(p)))
55. for i in xrange(5):
56.     p = 5 - i
57.     poq.put((p,count.next(),"a"+str(p)+str(i+5)))
58.     poq.put((p,count.next(),"b"+str(p)+str(i+5)))
61. size = poq.qsize()
62. print "priority ordered queue item size:%s" %size
63. print "priority ordered queue items:"
64. for i in xrange(size):
65.     print poq.get()

輸出類似如下：

1. queue item size:20
2. queue items:
3. a5
4. b5
5. a4
6. b4
7. a3
8. b3
9. a2
10. b2
11. a1
12. b1
13. a55
14. b55
15. a46
16. b46
17. a37
18. b37
19. a28
20. b28
21. a19
22. b19
23. priority queue item size:20
24. priority queue items:
25. (1, 'a1')
26. (1, 'a19')
27. (1, 'b1')
28. (1, 'b19')
29. (2, 'a2')
30. (2, 'a28')
31. (2, 'b2')
32. (2, 'b28')
33. (3, 'a3')
34. (3, 'a37')
35. (3, 'b3')
36. (3, 'b37')
37. (4, 'a4')
38. (4, 'a46')
39. (4, 'b4')
40. (4, 'b46')
41. (5, 'a5')
42. (5, 'a55')
43. (5, 'b5')
44. (5, 'b55')
45. priority ordered queue item size:20
46. priority ordered queue items:
47. (1, 8, 'a1')
48. (1, 9, 'b1')
49. (1, 18, 'a19')
50. (1, 19, 'b19')
51. (2, 6, 'a2')
52. (2, 7, 'b2')
53. (2, 16, 'a28')
54. (2, 17, 'b28')
55. (3, 4, 'a3')
56. (3, 5, 'b3')
57. (3, 14, 'a37')
58. (3, 15, 'b37')
59. (4, 2, 'a4')
60. (4, 3, 'b4')
61. (4, 12, 'a46')
62. (4, 13, 'b46')
63. (5, 0, 'a5')
64. (5, 1, 'b5')
65. (5, 10, 'a55')
66. (5, 11, 'b55')