extracting a heapq in a for loop - there must be more elegant solution

Helmut Jarausch jarausch at igpm.rwth-aachen.de
Wed Dec 4 10:44:49 CET 2013


On Wed, 04 Dec 2013 08:13:03 +1100, Cameron Simpson wrote:

> On 03Dec2013 12:18, Helmut Jarausch <jarausch at igpm.rwth-aachen.de> wrote:
>> I'd like to extracted elements from a heapq in a for loop.
>> I feel my solution below is much too complicated.
>> How to do it more elegantly? 
> 
> I can't believe nobody has mentioned PriorityQueue.
> 
> A PriorityQueue (from the queue module in python 3 and the Queue
> module in python 2) is essentially just a regular Queue using a
> heapq for the storage.
> 
> Example (untested):
> 
>   from Queue import PriorityQueue
> 
>   PQ = PriorityQueue()
>   for item in [1,2,3,7,6,5,9,4]:
>     PQ.put(item)
> 
>   while not PQ.empty():
>     item = PQ.get()
>     ... do stuff with item ...
> 
> I iterate over Queues so often that I have a personal class called
> a QueueIterator which is a wrapper for a Queue or PriorityQueue
> which is iterable, and an IterablePriorityQueue factory function.
> Example:
> 
>   from cs.queues import IterablePriorityQueue
> 
>   IPQ = IterablePriorityQueue()
>   for item in [1,2,3,7,6,5,9,4]:
>     IPQ.put(item)
> 
>   for item in IPQ:
>     ... do stuff with item ...
> 
> Cheers,

Many thanks!

I think you QueueIterator would be a nice addition to Python's library.
Helmut



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