Here's what I use for rot13:
rot13=: {&((65 97+/~i.2 13) |.@[} i.256)&.(a.&i.)
If I wanted to generalize that, I would probably go with:
rotN=: 1 :'rot13=: {&((65 97+/~i.2,m) |.@[} i.256)&.(a.&i.)'
13 rotN 'testing'
grfgvat
13 rotN rot13 'testing'
testing
--
Raul
On Fri, Dec 23, 2011 at 11:00 AM, Lorenzo Costanzia di Costigliole
<lorenzo.costan...@gmail.com> wrote:
> NB. What is the most elegant way to rotate uppercase
> NB. and lowercase letters by n? ("rotation cipher")
>
> c2n=: a.&i.
>
> lc=: >&96 *. <&123
> uc=: >&64 *. <& 91
>
> s=: 'Btggn Rwgxhibph 2011 id iwt Y-Egdvgpbbxcv bpxaxcv axhi!'
>
>
>
> NB. I came up with those, but I think there’s still room for improvement
> NB. (Isn't there something in the J-Phrases?)
>
> NB. uppercase -> 2, lowercase -> 1, else -> 0
> cl=: +:@uc + lc
> cl`(] , ([: 26&| +&n)&.(-&97) ,: ([: 26&| +&n)&.(-&65))}&.c2n s
>
> ((] + ] ]`([: 26&| n + ])@.((0~:[)"0) [ - ]) (97&*@lc + 65&*@uc))&.c2n s
>
> NB. Enumerate all possibilities
> |: ((] + ] (26 # ])`([: 26&| (i.26) + ])@.((0 ~: [)"0) [ - ]) (97&*@lc
> + 65&*@uc))&.c2n s
>
> NB. Thanks!
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