[R] how to rotate elements in a vector and points in a plane

[David Winsemius]

On Apr 23, 2010, at 1:54 PM, Ondřej Mikula wrote:

> Dear R-helpers,
>
> I need two simple functions, I guess they exist in R, but I am unable
> to find them.
> The first function should cyclically rotate elements in a vector.
> ("guyrot" in the package "wavethresh" should do it, but there's some
> problem with its loading)

 > rot <- function(x) (1:x %% x) +1
 > rot(9)
[1] 2 3 4 5 6 7 8 9 1
 > rotvec <- function(vec) vec[rot(length(vec))]

 > rotvec(c(3,4,5,6,7))
[1] 4 5 6 7 3

> The second function should rotate points in 2D by a given angle (about
> the defined point).

That's all the homework I choose to do today.

>
> Thanks for any advice
> Ondra Mikula
>
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David Winsemius, MD
West Hartford, CT