Re: fast search of NSPointerArray
Re: fast search of NSPointerArray
- Subject: Re: fast search of NSPointerArray
- From: James Maxwell <email@hidden>
- Date: Sat, 22 Jun 2013 20:25:53 -0700
It's a mixed graph structure. Basically, I'm storing all unique nodes in an NSMutableArray, then using NSPointerArrays to build the adjacency lists. It works really nicely for learning/building the graph, but it does seem as though searches are a little slower. My guess is that this is because I'm now iterating over a lot of null values (which I wasn't before). But, as Graham says, I should really verify this before going any further with altering the data structures...
J.
On 2013-06-22, at 8:10 PM, Ken Thomases <email@hidden> wrote:
> On Jun 22, 2013, at 9:56 PM, James Maxwell wrote:
>
>> I've recently been working on an optimized version of a pretty complex project. The big problem before was memory usage, and I'm happy to say that I've tackled that really well. However, in order to do this I switched from using NSMutableDictionaries to sparse NSPointerArrays. On the down side, I'm finding that the new build is a little bit slower -- an outcome I really didn't expect. Thinking through it a bit, it occurred to me that it may be because my data structures are now sparse arrays, with the data stored by index, and thus generally contain a fairly large number of null values. I'm thinking that my iterations may have slowed down because of the sparseness. Is there some decent way around this?
>>
>> I've thought creating my sparse arrays using NSHashTable (keyed by NSIntegers) instead of NSPointerArray. Does this seem like a reasonable way to speed things up?
>
> It's really hard to say. You should probably start at the high level and ask about data structures and algorithms that can achieve the sort of memory-time tradeoff you want. What is it that you're trying to achieve?
>
> Regards,
> Ken
>
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