I haven't done timings to check, but my recollection is that Roger implements the Boyer-Moore algorithm.
Henry Rich On 1/5/2011 3:04 PM, Dan Bron wrote: > [email protected] >> What is the fastest way to calculate the indices for all exact matches > from >> k that exist in v. > > The naive approach in J would be I.@:E. (or just E. if we wanted a > boolean mask instead of an index list): > > ss=:I.@:E. > > ('hello j';'software community') ss L:0 'hello j software > community ...' > +-+-+ > |0|8| > +-+-+ > > Notationally speaking, J could run this code in parallel (the DoJ makes no > promises about execution order), but currently J is single-threaded and will > run the searches in series. > > Faster approaches are probably possible, such as looking for shared > sub-sequences among the sought strings first, but I'll leave that for people > who enjoy code optimization. > > -Dan > > > > > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
