Re: [R] forecasting a time series

2012-01-20 Thread nhomeier
Hi Michael,

I think you're right, I should be looking for predict instead of 
forecast. I'm still fairly new to R so often don't know what to look 
for. As a simplified example (let's neglect the fourier terms):

fit = auto.arima(data)

but now I have data.latest, so I want to use the ARIMA terms from fit 
but with data.latest

I'll look into predicting, thank you


On 1/20/2012 1:35 AM, Michael Weylandt [via R] wrote:
 Can you clarify what exactly you mean by this?

 [N]ow [I] would like to use the last X values to predict tomorrow's
 weather. I'm at a loss. All the functions I've come across (like
 forecast()) use the series and then forecast from the end point.

 It sounds like a prediction to me.

 Anyways, I think most methods do allow new values for the
 independent variables: e.g., the newdata argument to most predict()
 methods and the xreg arguments to forecast::forecast(). Do you know
 which method you are using?

 Hope this helps,

 Michael

 On Wed, Jan 18, 2012 at 4:17 PM, nhomeier [hidden email] 
 /user/SendEmail.jtp?type=nodenode=4312525i=0 wrote:

  Couldn't find this in the archives. I'm fitting a series of historical
  weather-related data, but would like to use the latest values to 
 forecast.
  So let's say that I'm using 1970-2000 to fit a model (using fourier 
 terms
  and arima/auto.arima), but now would like to use the last X values to
  predict tomorrow's weather. I'm at a loss. All the functions I've come
  across (like forecast()) use the series and then forecast from the end
  point.
 
  Do I need to decompose the fit and write it out the long way? For 
 example,
  Tomorrow = fit$coef[1]*Yesterday + fit$coef[2]*BeforeYesterday + etc
 
  or is there a function that I'm not finding?
 
  Thank you,
  Nicole
 
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Re: [R] forecasting a time series

2012-01-19 Thread R. Michael Weylandt
Can you clarify what exactly you mean by this?

[N]ow [I] would like to use the last X values to predict tomorrow's
weather. I'm at a loss. All the functions I've come across (like
forecast()) use the series and then forecast from the end point.

It sounds like a prediction to me.

Anyways, I think most methods do allow new values for the
independent variables: e.g., the newdata argument to most predict()
methods and the xreg arguments to forecast::forecast(). Do you know
which method you are using?

Hope this helps,

Michael

On Wed, Jan 18, 2012 at 4:17 PM, nhomeier nhome...@aer.com wrote:
 Couldn't find this in the archives. I'm fitting a series of historical
 weather-related data, but would like to use the latest values to forecast.
 So let's say that I'm using 1970-2000 to fit a model (using fourier terms
 and arima/auto.arima), but now would like to use the last X values to
 predict tomorrow's weather. I'm at a loss. All the functions I've come
 across (like forecast()) use the series and then forecast from the end
 point.

 Do I need to decompose the fit and write it out the long way? For example,
 Tomorrow = fit$coef[1]*Yesterday + fit$coef[2]*BeforeYesterday + etc

 or is there a function that I'm not finding?

 Thank you,
 Nicole

 --
 View this message in context: 
 http://r.789695.n4.nabble.com/forecasting-a-time-series-tp4308147p4308147.html
 Sent from the R help mailing list archive at Nabble.com.

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 and provide commented, minimal, self-contained, reproducible code.

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[R] forecasting a time series

2012-01-18 Thread nhomeier
Couldn't find this in the archives. I'm fitting a series of historical
weather-related data, but would like to use the latest values to forecast.
So let's say that I'm using 1970-2000 to fit a model (using fourier terms
and arima/auto.arima), but now would like to use the last X values to
predict tomorrow's weather. I'm at a loss. All the functions I've come
across (like forecast()) use the series and then forecast from the end
point. 

Do I need to decompose the fit and write it out the long way? For example, 
Tomorrow = fit$coef[1]*Yesterday + fit$coef[2]*BeforeYesterday + etc

or is there a function that I'm not finding?

Thank you,
Nicole

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http://r.789695.n4.nabble.com/forecasting-a-time-series-tp4308147p4308147.html
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and provide commented, minimal, self-contained, reproducible code.