The paper I cited, *Hashing for Tolerant Index-Of<http://www.jsoftware.com/papers/Hashing.htm> * , presents a "monster" that defeats a sorting algorithm. (Defeat in the sense of causing it take quadratic time.)
On Mon, Jan 16, 2012 at 8:07 AM, Henry Rich <henryhr...@nc.rr.com> wrote: > You can sort the lists and then compare adjacent values; find > superfluous ones; then i.!.0 to find them in the original list. > > A tricky part is that proximity is not a transitive property. If the > tolerance is 2, and the data is > > 1 2 3 4 5 6 7 > > what should the result of the i.~ be? > > Henry Rich > > On 1/16/2012 10:06 AM, Raul Miller wrote: > > First: I like Roger Hui's response. And, in essence, it's doing > > exactly what you suggest. However, this requires comparing every > > number in the left list with every number in the right list. I am > > currently pondering algorithms which rely on I. so that when the lists > > are long computation times are still reasonable (perhaps with 100000 > > members in each list). > > > > Second: I would want the three PI values in my original message to be > > treated as equal. I want to be able to specify a magnitude of > > acceptable difference which is greater than any of the differences in > > that data sample. > > > > FYI, > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
