[R] exponential smoothing

[Adrian Trapletti]

> Date: Fri, 14 Jun 2002 13:21:23 +0200
> From: Xavier.Abulker at fimat.com
> Subject: [R] exponential smoothing
>
> could someone help me to write a fonction doing an exponential smoothing in
> case of a multivariate time serie?
> I tried
> ewma <- function (x, lambda = 1, init = 0)
> {
>      if (is.ts(x))
>        filter(lambda*x, filter=1-lambda, method="recursive", init=init)
>      else
>        stop(message="first argument should be a time serie")
> }
> but I can't apply that to multivariate
> Thanks
>
> xavier
>

For example:

apply(x,FUN=ewma,2,lambda=0.1)

should work. You maybe need to set the default of init in ewma() to x[1].

best
Adrian

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