Re^2: getting elements from an array based on a value not in the array

lima1,
If we assume that one and only one output exists for a given $target then @test must always be sorted. Assuming that as a given, the best approach is a modified binary search.

The only way caching seems to make sense to me is if the list of $target(s) can contain duplicates. I can think of some other scenarios but they are highly dependent on details we don't have.

For instance, if $target will only ever be integers we could fill a hash with the integers between numbers in @test with a value of the @test index (N.5 since $target is missing). Then we need only lookup up $target in our hash, get the index and return a slice with $size elements on either side. The entire hash could be built all at once up front or it could be built "as you go" which would be a win if the list of $target(s) were clustered.

The trouble is that this is all highly speculative. More information and cleare explanation is required for a decent solution in my opinion.

Cheers - L~R

Comment on Re^2: getting elements from an array based on a value not in the array

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Re^3: getting elements from an array based on a value not in the array by lima1 (Curate) on Aug 11, 2006 at 19:55 UTC
yes, exactly. I would have implemented the cache as an hash with key $target and value the offset of splice. but you are right. binary search is the best solution if we understood the OP right.	[reply]