Oh... so one needs to, say, assign the result to see the real t/s? Thanks,
Mike Sent from my iPad > On 16 May 2020, at 17:05, Henry Rich <[email protected]> wrote: > > The time/space numbers are telling you that (x $ y) produces a virtual result > when it can, while (_2 ]\ y) doesn't (yet). If you use the result > immediately, the space saving is real. If you box the result or save it in a > name, the value will be realized and the space saving will vanish. > > Henry Rich > >> On 5/16/2020 11:14 AM, 'Michael Day' via Programming wrote: >> Much neater than what I was about to offer, unless Raoul needs to specify >> the fill, >> >> in which case, this alternative rather minimal amendment is worth >> consideration: >> >> ($!._ ~2,~>.@-:@#) i.7 >> 0 1 >> 2 3 >> 4 5 >> 6 _ >> >> cf >> >> _2]\ i.7 >> 0 1 >> 2 3 >> 4 5 >> 6 0 >> >> Also, the time and space performance _might_ be important for large inputs: >> >> ts' $ _2]\ list ' [list =: i.100000 >> 0.000618 1.04986e6 >> ts'($!._ ~2,~>.@-:@#) list' >> 2.7e_6 2304 >> >> Cheers, >> >> Mike >> >>> On 16/05/2020 15:57, 'Rob Hodgkinson' via Programming wrote: >>> You could try Infix … here with NuVoc link… >>> https://code.jsoftware.com/wiki/Vocabulary/bslash#dyadic >>> >>> x u\ y where x is eg _2 means apply very b to successive pairs (_ for >>> non-overlapping). >>> >>> _2 ]\ 1 2 3 4 5 6 >>> 1 2 >>> 3 4 >>> 5 6 >>> _2 ]\ 1 2 3 4 5 6 7 >>> 1 2 >>> 3 4 >>> 5 6 >>> 7 0 >>> >>> _2 <\ 1 2 3 4 5 6 >>> ┌───┬───┬───┐ >>> │1 2│3 4│5 6│ >>> └───┴───┴───┘ >>> >>> HTH…/Rob >>> >>>> On 17 May 2020, at 12:42 am, Raoul Schorer <[email protected]> wrote: >>>> >>>> Hello, >>>> >>>> I am convinced that this must be trivial, but I wasn't able to find in the >>>> documentation how to reshape a list to a table without manually extracting >>>> the length. >>>> >>>> in summary, is there a more direct way of doing: >>>> >>>> lst =. i. 6 >>>> >>>> ((2,~2%~#) $ ]) lst >>>> >>>> for a list of arbitrary length? >>>> >>>> Thanks! >>>> >>>> Raoul >>>> >>>> ---------------------------------------------------------------------- >>>> For information about J forums see http://www.jsoftware.com/forums.htm >>> ---------------------------------------------------------------------- >>> For information about J forums see http://www.jsoftware.com/forums.htm >> >> > > > -- > This email has been checked for viruses by AVG. > https://www.avg.com > > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
