[R] analog to the matlab buffer function?

[Gregory R. Warnes]

The gtools package also includes a function, 'running', which accomplishes
the desired task:

> library(gtools)
> t(running(1:5, width=3, fun=c))
    [,1] [,2] [,3]
1:3    1    2    3
2:4    2    3    4
3:5    3    4    5
>  


On 11/30/06 8:56 PM, "Marc Schwartz" <marc_schwartz at comcast.net> wrote:

> Here is another possibility, though I may be missing how the Matlab
> function handles incomplete rows generated at the end of the source
> vector. I have not fully tested this, so it may yet require some
> tweaking and certainly appropriate error checking.
> 
> I am presuming that the basic premise is that each row is of length
> 'window' and that it overlaps with the END of prior row by 'overlap'.
> 
> 
> Buffer <- function(x, window, overlap)
> {
>   Res <- NULL
> 
>   while (length(x) >= window)
>   {
>     Res <- c(Res, x[1:window])
>     x <- x[(1 + window - overlap):length(x)]
>   }
> 
>   matrix(Res, ncol = window, byrow = TRUE)
> }
> 
> 
>> Buffer(1:5, 3, 2)
>      [,1] [,2] [,3]
> [1,]    1    2    3
> [2,]    2    3    4
> [3,]    3    4    5
> 
>> Buffer(1:10, 4, 2)
>      [,1] [,2] [,3] [,4]
> [1,]    1    2    3    4
> [2,]    3    4    5    6
> [3,]    5    6    7    8
> [4,]    7    8    9   10
> 
> HTH,
> 
> Marc Schwartz
> 
> 
> On Thu, 2006-11-30 at 16:32 -0800, Charles C. Berry wrote:
>> See
>> 
>> ?embed
>> 
>> It is not quite the same, but this seems to be what you want - at least
>> for the example you give:
>> 
>>> t( embed(1:5,3) )[3:1,]
>>       [,1] [,2] [,3]
>> [1,]    1    2    3
>> [2,]    2    3    4
>> [3,]    3    4    5
>>> 
>> 
>> On Fri, 1 Dec 2006, Martin Ivanov wrote:
>> 
>>> Hello! I am new to R. I could not find a function analogous to matlab's
>>> function buffer, which is used in signal processing. Is there such a
>>> function in R? What I need to do is as follows. If I apply the function
>>> to the vector c(1:5) for example with a window length 3 and overlapping
>>> 2, I need to get a matrix like this:
>>> 1 2 3
>>> 2 3 4
>>> 3 4 5
>>> In matlab this is achieved with the function buffer. Is there ananalogous R
>>> function?
> 
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