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
>
--
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