Re: Mutually exclusive item filtering-comparing
Re: Mutually exclusive item filtering-comparing
- Subject: Re: Mutually exclusive item filtering-comparing
- From: Jens Alfke <email@hidden>
- Date: Tue, 05 Nov 2013 15:00:47 -0800
On Nov 5, 2013, at 2:47 PM, Chris Paveglio <email@hidden> wrote:
> Could you expand on that a bit or maybe send me a link for more info? My ID numbers aren't sequential from 0 to 100. They are somewhat random (457, 853, 1587, etc). An example would be {item1ID: 234, itemID2: 3987, exclusive:yes}. From your explanation, would a bitmap index work? Adding my item# together and multiply n wouldn't give a real offset to a bit in a bitmap.
If the item numbers are too large to practically use a bitmap, you can use a hashtable instead. In Cocoa terms, create an NSMutableSet whose keys are pairs of itemIDs. The simplest key type would be an NSArray of two NSNumbers, but it’s cheaper to combine the two numbers into one object, for instance by packing them into the upper and lower halves of a 64-bit integer.
—Jens
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