Small correction: '[ -: $@($,)'
On 8/21/20, Joseph Novakovich <[email protected]> wrote: > I would expect '[ -: $@$' to hold, which this would break. > > Cheers > > On 8/21/20, 'Rob Hodgkinson' via Programming <[email protected]> > wrote: >> Henry I am just clarifying here but not advocating one way or the other >> …. >> >> This feature is part of q (or k) and is implemented as an extension of >> the >> reshape function (which is # in q). >> >> Here is a q sample, >> >> q)args:("Code";33;"Name";"Iverson";"Age";34) /Comment: >> Here >> my list might be of Key/Value pairs >> >> q)args >> "Code" >> 33 >> "Name" >> "Iverson" >> "Age" >> 34 >> >> q)0N 2#args >> /Comment: q uses the NULL value (0N) to say “I know the list is in >> pairs, so work out the rows" (hence here 3 x 2) >> "Code" 33 >> "Name" "Iverson" >> "Age” 34 >> >> >> The equivalent mechanism in APL or J is along these lines: >> >> args=: 'Code';33;'Name';'Iverson';'Age';34 >> >> ((($args)%2),2)$args /Comment: To save entering >> this >> phrase in J, David is proposing to use the _ character to request it be >> computed, so ( _ 2$args) would produce the same >> ┌────┬───────┐ >> │Code│33 │ >> ├────┼───────┤ >> │Name│Iverson│ >> ├────┼───────┤ >> │Age │34 │ >> └────┴───────┘ >> >> The feature was an enhancement of the shape function in q, mostly useful >> where the list contained repeated groups. >> >> I am not advocating or rejecting it, just pointing out it was a handy >> convenience in limited cases. >> >> …/Regards Rob >> >>> On 21 Aug 2020, at 10:40 am, Henry Rich <[email protected]> wrote: >>> >>> I don't think it fits into the language where you want to put it. >>> >>> (x $ y) is to be used when you know what you want the shape to be. It >>> sounds like you are guessing at it, and asking $ to make a plausible >>> guess. I say that is a different function. >>> >>> The fact that you can handle only one infinity is a warning signal that >>> the definition is incomplete. >>> >>> Henry Rich >>> >>> On 8/20/2020 8:33 PM, David Lambert wrote: >>>> The proposal is for dyadic $ only. >>>> >>>> Processing experimental data which sometimes arrives in irregular >>>> chunks >>>> I often end up with a vector. >>>> q: # data >>>> helps me figure out how to match data to the experiment. The proposal >>>> solves the case where one of the inner shape atoms is unknown. >>>> >>>> If this is a sufficiently common situation, and Pascal shows interest, >>>> it >>>> might be a worthwhile extension. On the other hand, the >>>> implementations >>>> presented meet need, and I have these. It breaks only the unlikely >>>> programs that depend on _ triggering an error. J need only check for >>>> infinity if x is float, and I'd think the engine already tests the type >>>> of x. >>>> >>>> |On Tuesday, August 18, 2020, 07:51:03 p.m. EDT, Henry Rich >>>> <[email protected]> wrote: >>>> |This is a proposed change only to dyad and $ , is that right? >>>> |What problem does this solve? >>>> >>>> ---------------------------------------------------------------------- >>>> 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 >> > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
