Priority function for Priority Queue in Python

Question

How would I write the following Java PriorityQueue in Python?

PriorityQueue<Integer[]> pq = new PriorityQueue<Integer[]>(11,
        new Comparator<Integer[]>() {
          public int compare(Integer[] A, Integer[] B) {
            return A[0] < B[0] ? -1 : 1;
          }
        });

I got as far as

from Queue import PriorityQueue
def my_method(self):
  pq = # I got stuck here since I need to include "comparator"

I have looked through many examples such as Creating a python priority Queue but they don't seem to be defining a priorty function or comparator of some sort.

Is this another pathetic down-vote? Is this from the guy whose response got down-voted so that he deleted his response. I didn't down-vote your response -- although I should have since it was way off. — learner, Jan 28 '13 at 23:39

score 1 · Accepted Answer · answered Jan 28 '13 at 23:35

1

One option is to put (A.pulp, A) as the values in your priority queue. That way, it will use tuple comparisons to compare pulp values first.

Another option is to implement __cmp__ (or define __lt__ and __eq__ and use functools.total_ordering) on your class to do the necessary comparisons. This assumes you don't have some other comparison function in place already.

answered Jan 28 '13 at 23:35

nneonneo

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Can you show an example or a link of how I would write the PriorityQueue with the comparison function? – learner Jan 28 '13 at 23:41
In the second case you'd be writing the class with the comparison function. – nneonneo Jan 28 '13 at 23:42
What if `A` was actually a list and `A.pulp` was the first element of the list, as in `A=[5,1,7,9,2]`. How should `pq.put(A[0],A)` work? It does not seem to be working for me. – learner Jan 29 '13 at 04:25
Put a tuple: `pq.put((A[0], A))` – nneonneo Jan 29 '13 at 06:15
instead of `(A.pulp, A)` what actually works is `([A.pulp, A])` – learner Jan 29 '13 at 15:11

Priority function for Priority Queue in Python

1 Answers1