[issue18241] Add unique option to heapq functions

[Raymond Hettinger]

Change by Raymond Hettinger :


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resolution:  -> rejected
stage:  -> resolved
status: open -> closed

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[issue18241] Add unique option to heapq functions

[Irit Katriel]

Irit Katriel  added the comment:

I would dedup when extracting items from the queue, because it is trivial to 
find duplicates then. It can be done with a simple wrapper, without any changes 
to the queue.

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nosy: +iritkatriel

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[issue18241] Add unique option to heapq functions

[Antoine Pitrou]

New submission from Antoine Pitrou:

In one application, I would like to use a heap as an allocation pool. I also 
want to check that a given value isn't released twice, therefore that the heap 
contains unique values. My use case would be solved nicely if heappush() took 
an optional unique=False parameter.

Note that I haven't checked if doing so is possible while maintaining the O(log 
n) complexity :-)

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messages: 191341
nosy: pitrou, rhettinger
priority: low
severity: normal
status: open
title: Add unique option to heapq functions
type: enhancement
versions: Python 3.4

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[issue18241] Add unique option to heapq functions

[Serhiy Storchaka]

Serhiy Storchaka added the comment:

No, it's impossible without additional structure. And with a set it is trivial.

def uniqueheappush(heap, inheap, item):
if id(item) in inheap:
return False
heappush(heap, item)
inheap.add(id(item))
return True

def uniqueheappop(heap, inheap):
item = heappop(heap, inheap)
inheap.discard(id(item))
return item

I recomend reject this issue.

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nosy: +serhiy.storchaka

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[issue18241] Add unique option to heapq functions

[Antoine Pitrou]

Antoine Pitrou added the comment:

 No, it's impossible without additional structure. And with a set it is 
 trivial.

Yeah, I wanted to avoid the memory overhead of a set.

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