[R] Odp: Help me with prediction in linear model

[Petr PIKAL]

Hi

r-help-bounces at r-project.org napsal dne 24.07.2010 11:48:11:

> 
> Thanks Murphy and pikal,
> 
> I need another help,for fitting first fourier transformation ,i used
> following thing .Please advise on this
> 
> 
> beer_monthl has 400+ records
> 
> EXample:
> > head(beer_monthly)
>   beer
> 1 93.2
> 2 96.0
> 3 95.2
> 4 77.1
> 5 70.9
> 6 64.8
> 
> 
> 
> 
> time<-seq(1956,1995.2,length=length(beer_monthly))

Even this is "not working"

time<-seq(1956,1995.2,length=length(beer_monthly))
Error in seq.default(1956, 1995.2, length = length(beer_monthly)) : 
  object 'beer_monthly' not found

> sin.t<-sin(2*pi*time)
> cos.t<-cos(2*pi*time)
> beer_fit_fourier=lm(beer_monthly[,1]~poly(time,2)+sin.t+cos.t) #this is 
not
> working

gives me result without error

> beer_fit_fourier=lm(beer_monthly[,1]~time+time2+sin.t+cos.t) #it is 
working
> 
> 
> #prediction is not workinng
> 
> tpred_four <- data.frame(time = seq(1995, 1998, length = 20))
> predict(beer_fit_fourier, newdata = tpred_four)
> 

You'd rather read some documentation about lm and predict. You do not have 
variables sin.t and cos.t in your newdata.

Please do read docs, posting guide and provide reproducible example.

> Is there any way to fit first fourier  frequency ,
> 
> Please assist.
> 
> Thanks in advance
> 
> 
> 
> 
> 
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