On Thu, 01-Dec-2011 at 10:13AM -0800, lglew wrote:
|> Hi R-users,
|>
|> I'm trying to produce decompositions of a multiple time-series, grouped by a
|> factor (called "area"). I'm modifying the code in the STLperArea function of
|> package ndvits, as this function only plots produces stl plots, it does not
|> return the underlying data.
|>
|> I want to extract the trend component of each decomposition
|> ("x$time.series[,trend]), assign a name based on the factor "area".
|>
|> My input data look like this:
|> Area is a factor, with three (but could be many more) levels.
|> area
|> 1
|> 2
|> 3
|>
|> Ystart=2000
|>
|> TS is a timeseries:
|>
|> X2000049 X2000065 X2000081 X2000097 X2000113
|> 1 0.2080 0.2165 0.2149 0.2314 0.2028
|> 2 0.1578 0.1671 0.1577 0.1593 0.1672
|> 3 0.1897 0.1948 0.2290 0.2292 0.2067
|>
|> Here's the function:
|>
|> STLpA<-function(TS, area, Ystart, period=23, nSG="5,5", DSG=0)
|> {
|> require (RTisean)
|> for(i in 1:unique(area)){
|> vi.metric=TS[area==i]
|> filt.vi<-sav_gol(vi.metric,n=nSG,D=DSG)
|> vi.sg<-ts(filt.vi[,1], start=Ystart,frequency=period)
|> stld.tmp<-stl(vi.sg, s.window="periodic", robust=TRUE, na.action=na.approx)
|> stld.trend<-stld.temp$time.series[,trend]
|> }
|> assign(paste("stld", i , sep= "."), stld.trend)
|> vi.trend<-ls(pattern= "^stld..$")
|> return(vi.trend)
|> }
|>
|> When I call this function with signal=STLpA(TS,area,Ystart=2000,period=23,
|> nSG= "5,5", DSG="0"))
|>
|> I get this error:
|>
|> Error in cat(list(...), file, sep, fill, labels, append) :
|> argument 1 (type 'list') cannot be handled by 'cat'
|> In addition: Warning message:
|> In 1:unique(area) :
|> numerical expression has 3 elements: only the first used
|>
|> I'm guessing this is because I'm assigning names to each temporary stl.trend
|> file incorrectly. Can anyone
|> improve on my rather poor efforts here?
I would suggest putting your individual trends into a list and
returning that at the end of your function rather than trying to
assing individual objects. IMHO it's easier to do and more useful.
Something along these lines:
> trends <- list()
> for(i in 1:unique(area)){
...
+ trends[[i]] <- ....
}
Then you'll have an element in the list trends that you do with what
you will. It creates less clutter also.
HTH
--
~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.
___ Patrick Connolly
{~._.~} Great minds discuss ideas
_( Y )_ Average minds discuss events
(:_~*~_:) Small minds discuss people
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