Re: [R] Exponential Smoothing: Forecast package

2010-06-29 Thread Stephan Kolassa
Hi Phani, something like this looks promising: # library(forecast) library(Mcomp) MAPE.for.Holt <- function (x,series,bignum=10e6) { foo <- try(ets(series$x,model="AAN",damped=FALSE,alpha=x[1],beta=x[2],restrict=FALSE),silent=TRUE) if ( class(f

Re: [R] Exponential Smoothing: Forecast package

2010-06-28 Thread phani kishan
Hey, Thanks for the tip Stephan. But you could tell me how to pass the series to the function calling ets? Initially I planned to do it this way: wrapper<-function(x) { alpha<-x[1] beta<-x[2] ph<-x[3] series<-x[4] foofit<-ets(series,model="AZZ",alpha=alpha,beta=beta,phi=phi,additive.only=T,opt.cri

Re: [R] Exponential Smoothing: Forecast package

2010-06-28 Thread Stephan Kolassa
Hi Phani, to get the best Holt's model, I would simply wrap a suitable function calling ets() within optim() and optimize for alpha and beta - the values given by ets() without constraints would probably be good starting values, but you had better start the optimization with a variety of star

[R] Exponential Smoothing: Forecast package

2010-06-28 Thread phani kishan
Hey, I am using the ets() function in the forecast package to find out the best fit parameters for my time-series. I have about 50 sets of time series data. I'm currently using the function as follows: ets(x,model="AZZ",opt.crit="mse") As to my observation about 5-10 of them have been identifie