[R] another matrix problem

[Erich Neuwirth]

rotateleft<-function(vec,offset)
     vec[(((0:(length(vec)-1))+offset) %% length(vec)) + 1]
rotateright<-function(vec,offset)rotateleft(vec,length(vec)-offset)
rotatedcols<- 
function 
(vec 
,offsets)do.call(cbind,lapply(offsets,function(x)rotateright(vec,x)))

rotatedcols(1:5,0:2)

is perhaps what you want

On Jul 5, 2009, at 2:54 PM, William Simpson wrote:

> I want a function that takes an input vector, the number of columns
> and returns a matrix as follows.
>
> x<- 1:5
>
> foo(x, nc=3)
>
> 1 5 4
> 2 1 5
> 3 2 1
> 4 3 2
> 5 4 3
>
> Thanks again for any help.
>
> Bill
>
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>

--
Erich Neuwirth
Didactic Center for Computer Science and Institute for Scientific  
Computing
University of Vienna