A bit of an explanation to the answer ":"0 i.4 0 1 2 3
converts numbers to text representation. 'm'(,":)"0 i.4 or 'm' ,"0 1 ": "0 i.4 will provide the same answer Raul gave. ----- Original Message ----- From: Raul Miller <[email protected]> To: Programming forum <[email protected]> Cc: Sent: Friday, February 7, 2014 5:46:37 PM Subject: Re: [Jprogramming] k's for each, for each left, for each right in j ' would be either "0 (or equivalently "+) or &.> f'x would be either f"0 x (or equivalently f"+ x) for flat x or f&.> x (or, equivalently f each x) for running f inside boxes of x And I think you want 'm'&,@":"0 i.4 though there are other ways of accomplishing that. J is not exactly equivalent to K and you'll need a bit of study to get used to it. I hope this helps, -- Raul On Fri, Feb 7, 2014 at 5:41 PM, Christopher A. Simon <[email protected]> wrote: > Sorry about lack of explanation, > > ' is for each. > > f'x is function f applied to each value of x, > > !4 in k is the same as i.4 in j > > monadic $ converts or casts to type char > > and , is append. > > ("m",)'$!4, could also be {[x]"m",x}'$!4 > > results in, > > ("m0" > "m1" > "m2" > "m3") > > What I'm having trouble translating are some of the loopless operations in > j. > > I think I have a basic handle on some of the vectorized operations, like > > 1 2 * 3 4 > > or > > +/i.5 "insert '+' into 0 1 2 3 4" right? > > But if I want to define a function, say append the character "m", and then > use the defined function in a vectorized fashion, I get a little lost. > > Thanks, > > -Chris > > > > > > > > On Fri, Feb 7, 2014 at 4:56 PM, Raul Miller <[email protected]> wrote: > >> I do not know exactly what ' \: and /: do in K - if I recall >> correctly, these are somewhat like rank specifications ("0) ("1 0) and >> ("0 1) except maybe use _ in place of 1 depending on what you want to >> do, and somewhat like the use of each (&.>) and possibly boxing either >> the left or right argument. >> >> It might be easier if you expressed the problem you are trying to >> solve in English, or if you could point at the relevant K >> documentation. I can't find enough on ("m",)'$!4 in documenation I can >> find -- stuff like http://www.kx.com/q/d/primer.htm or >> http://code.kx.com/wiki/Reference/BangSymbol or >> http://code.kx.com/wiki/Reference/DollarSign -- to say anything useful >> about that expression. >> >> Thanks, >> >> -- >> Raul >> >> On Fri, Feb 7, 2014 at 4:46 PM, Christopher A. Simon >> <[email protected]> wrote: >> > My apologies if this is not where newbies email with questions. >> > >> > I've become somewhat comfortable with k, in particular >> > >> > ' \: and /: >> > >> > But I haven't exactly found how to do similar operations j. >> > >> > I'm a little lost with, find the equivalent to, >> > >> > ("m",)'$!4 >> > >> > Any suggestions for transitioning from k to j, with respect to ' , \: >> and /: >> > >> > Thanks, >> > >> > -Chris >> > ---------------------------------------------------------------------- >> > For information about J forums see http://www.jsoftware.com/forums.htm >> ---------------------------------------------------------------------- >> For information about J forums see http://www.jsoftware.com/forums.htm >> > > > > -- > __________________________________________ > > Christopher Alex Simon > __________________________________________ > > (831) 239 0636 > > 113 Cedar Apt 5A > > New York, New York 10006, USA > ---------------------------------------------------------------------- > 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
