New submission from Carlos Ferreira: I'm using Priority Queues and followed the Python documentation for a simple example.
>From Queue documentation in Python 3.3 http://docs.python.org/3.3/library/queue.html " The lowest valued entries are retrieved first (the lowest valued entry is the one returned by sorted(list(entries))[0]). A typical pattern for entries is a tuple in the form: (priority_number, data). " Then I tried this simple code. >>> pq = PriorityQueue() >>> pq.put_nowait((0, {'a':1})) >>> pq.put_nowait((0, {'a':2})) Traceback (most recent call last): File "<stdin>", line 1, in <module> File "/usr/lib/python3.3/queue.py", line 187, in put_nowait return self.put(item, block=False) File "/usr/lib/python3.3/queue.py", line 146, in put self._put(item) File "/usr/lib/python3.3/queue.py", line 230, in _put heappush(self.queue, item) TypeError: unorderable types: dict() < dict() Is this a normal behaviour? I'm not sure if this should be declared as a bug... Instead of sticking to the first argument that indicates the priority, the heapq algorithm checks the second field and tries to order the dictionaries. I solved this annoyance by adding a third field, the object ID. Since the object ID is actually its address in memory, every object will have a different ID. Also, since the queue entries will have the same priority (zero), the id value is used to order the tuples in the heap queue. >>> pq = PriorityQueue() >>> a = {'a':1} >>> b = {'a':2} >>> pq.put_nowait((0, id(a), a)) >>> pq.put_nowait((0, id(b), b)) ---------- components: Interpreter Core messages: 187321 nosy: Claymore priority: normal severity: normal status: open title: Priority Queue type: behavior versions: Python 3.3 _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue17794> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
