[R] rollmean and stl

[Achim Zeileis]

On Tue, 22 Jul 2008, stephen sefick wrote:

> I need to investigate how rollmean and the trend returned from stl differ.
> I am trying to find out exactly what the trend part of stl is (I have just
> started coding in R and do not know fortran).  I need to extract this
> because it will be used in further calculations, and it needs to be verified
> to make sure that I am using the right process.   I would like to use this
> to remove the seasonal component  of a time series  to investigate the
> advective transport of oxygen and the local production.
>
> I tried
> d <- stl(data, s.window="periodic")
> d$trend
> and I get NULL

Look at the "Value" section of ?stl:

time.series: a multiple time series with columns 'seasonal', 'trend'
           and 'remainder'.

i.e., use

d$time.series[,"trend"]

> thanks
>
> Stephen
>
> -- 
> Let's not spend our time and resources thinking about things that are so
> little or so large that all they really do for us is puff us up and make us
> feel like gods. We are mammals, and have not exhausted the annoying little
> problems of being mammals.
>
> -K. Mullis
>
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