Beefy Boxes and Bandwidth Generously Provided by pair Networks
Keep It Simple, Stupid
 
PerlMonks  

Re: Re: Re: Data Structure needed for Event Queue

by demerphq (Chancellor)
on May 28, 2002 at 15:03 UTC ( #169787=note: print w/replies, xml ) Need Help??


in reply to Re: Re: Data Structure needed for Event Queue
in thread Data Structure needed for Event Queue

Just curious, but without my references im not really sure but what kind of heap is that? Fibonnacci?

Yves / DeMerphq
---
Writing a good benchmark isnt as easy as it might look.

  • Comment on Re: Re: Re: Data Structure needed for Event Queue

Replies are listed 'Best First'.
Re: Re: Re: Re: Data Structure needed for Event Queue
by danger (Priest) on May 28, 2002 at 16:29 UTC
    Just curious, but without my references im not really sure but what kind of heap is that? Fibonnacci?

    Assuming you are referring to the EoPwP heap that educated_foo points to, then (as stated by educated_foo, who refers to me in the plural :-) it is strictly a simple, array-based implementation of a binary heap. It isn't documented except as it is built in the book.

    A main difference between this and the Heap model is that this one contains the comparison routines internally and works on the model of selecting a comparison method on heap creation and supplying a suitable key and satellite data for each inserted element (it is easy to use any objects for which you can supply a key) --- to use objects with the Heap version you need all of your objects to supply their own cmp() method for comparing themselves with any other object type in the heap. The latter is more flexible because the comparison routines may be arbitrarily complex, but does require that all your objects either inherit or supply their own common comparison method.

Re: Re: Re: Re: Data Structure needed for Event Queue
by educated_foo (Vicar) on May 28, 2002 at 15:25 UTC
    Which "that"? Heap implements normal ("binary"), binomial, and fibonnacci heaps. The "Elements of" version is a normal binary heap.

    /s

      Hmm, I was reviewing AoP yesterday and it seemed to suggest that binary heaps arent particularly optimal. Wonder why they picked that one?

      Yves / DeMerphq
      ---
      Writing a good benchmark isnt as easy as it might look.

        I'd guess because (1) they're simple, and (2) they're fast enough. Fibonnacci heaps are probably one of the most complicated data structures known to man. Second, O(log N) is not that bad, so there's relatively little to be gained. Even though Fib heaps are O(1) amortized where binary heaps are O(log N), the constants are large enough that especially in Perl, they'll probably cause them to lose for most reasonable values of N. There isn't that much difference between O(log N) and O(1) (or O(log log N) for binomial), so constants can easily outweight the gains. For example:
        
              log N    log log N    1
        
        256   8        3            1
        
        1K    10       3.3          1
        
        1M    20       4.3          1
        
        
        So if inserting an item in a fibonnacci heap is 10 times as complicated as inserting one in a binary heap (not entirely unlikely), the binary heap is faster for 1000 elements.

        /s

Log In?
Username:
Password:

What's my password?
Create A New User
Domain Nodelet?
Node Status?
node history
Node Type: note [id://169787]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others taking refuge in the Monastery: (5)
As of 2022-05-18 12:05 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?
    Do you prefer to work remotely?



    Results (70 votes). Check out past polls.

    Notices?