[R] Questions for package ts prediction

[Prof Brian Ripley]

You have a scoping problem: the predict method needs to find the data:
please supply an explicit newdata argument.  Your first example works
because `y' happens to be globally visible and be the right object.

On 9 Jun 2003, zhu wang wrote:

> I am trying to write a function to return prediction values using
> package ts. I have written three different versions since I am not sure
> what's wrong with my func2. func and func1 return the same results.But
> func1 and func2 don't. In particular, the only difference between
> "func1" and "func2" is the function variable name being y and data,
> respectively.  But running the last line of the following script will
> give the message:
> 
> Error in ts(x): object is not a matrix.
> 
> I am confused. Also, could somebody kindly let me what's the answer if
> any for the following sunspot example from the package help:
> 
> data(sunspot)
> (sunspot.ar <- ar(sunspot.year)) 
> # why not just sunspot.ar <- ar(sunspot.year) ?

Have you tried it?  Please do so, and you will learn the difference!
This idiom is widely used in the R help files.

> predict(sunspot.ar, n.ahead=25)

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
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