\: and /: in k are special cases of J rank.
In k, x f\: y (each left) applies f between each item of x and the entire
of y, e.g.
k)a:1 2
k)b:10 20 30
k)a +\: b
11 21 31
12 22 32
The J equivalent would be to apply f with rank _1 _, i.e.
a=: 1 2
b=: 10 20 30
a +"_1 _ b
11 21 31
12 22 32
In J, this is the same as +/ i.e.
a +/ b
11 21 31
12 22 32
Also, the J equivalent of $!4 would be:
":each i.4
┌─┬─┬─┬─┐
│0│1│2│3│
└─┴─┴─┴─┘
To join 'm' to each:
'm' ,each ":each i.4
┌──┬──┬──┬──┐
│m0│m1│m2│m3│
└──┴──┴──┴──┘
or simply:
('m',":)each i.4
┌──┬──┬──┬──┐
│m0│m1│m2│m3│
└──┴──┴──┴──┘
On Sat, Feb 8, 2014 at 5:46 AM, Christopher A. Simon <
[email protected]> wrote:
> My apologies if this is not where newbies email with questions.
>
> I've become somewhat comfortable with k, in particular
>
> ' \: and /:
>
> But I haven't exactly found how to do similar operations j.
>
> I'm a little lost with, find the equivalent to,
>
> ("m",)'$!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
>
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For information about J forums see http://www.jsoftware.com/forums.htm
