> Trygve Inda wrote: > >> Each dictionary (or object with properties) will need to hold >> roughly 9 >> textual strings, and there will be on the order of 10,000 objects >> in the >> array. I am guessing that dictionary will perform better than a >> predicate >> filter given the number of objects. > > > Never guess at performance. Always measure. For one thing, "perform > better" may be irrelevant. "Good enough" is the only criterion worth > evaluating. If worse performance is good enough, then better > performance serves no purpose (ignoring other tradeoffs, such as > power consumption). If array search is 10 msecs, and dictionary > search is 10 usecs, the user will never perceive the thousand-fold > difference if the search occurs at most 10 times per sec. > > In addition, if the objects are ordered in the array, a binary search > instead of linear is simpler than managing a parallel dictionary for > keyed retrieval. Binary search is O(log2(n)) worst-case. > http://en.wikipedia.org/wiki/Binary_search_algorithm > > It almost seems like you're choosing representations and algorithms > primarily on the existence of classes, instead of what might work > best. That is, because predicate filter classes exist, you don't > have to write that class, so you've decided to use it for searching > arrays instead of other algorithms that may have substantially better > performance, but for which you'd have to write non-trivial code (or > find it on the web). And the only tradeoffs you're making are > between varieties of existing Apple-supplied classes, e.g. > NSDictionary vs. NSArray with predicate-search, rather than looking > for third-party classes.
This is probably true since this is a very minor part of my app... I simply need an array to display in a table with the added functionality of being able to locate a record uniquely (each object in the array has a unique ID as one of it's properties). T. _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
