[R] Assign name to object for each iteration in a loop.
David Winsemius
dwinsemius at comcast.net
Fri Dec 2 05:55:43 CET 2011
On Dec 1, 2011, at 1:13 PM, 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]
The line above will probably fail. It is more likely to succeed with:
stld.trend<-stld.temp$time.series[ ,"trend"]
Unless you have defined a variable named `trend` with a value of
"trend".
> }
> assign(paste("stld", i , sep= "."), stld.trend)
> vi.trend<-ls(pattern= "^stld..$")
> 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) :
You might want to use traceback() at this point to see which of hte
functions you did call is sending lists to `cat`.
> 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.
I'm guessing it's not that since I think that step would fail if you
got to it for the reasons described above.
> Can anyone
> improve on my rather poor efforts here?
>
> Many thanks,
>
> Louise
>
>
>
>
> --
> View this message in context: http://r.789695.n4.nabble.com/Assign-name-to-object-for-each-iteration-in-a-loop-tp4129752p4129752.html
> Sent from the R help mailing list archive at Nabble.com.
>
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> and provide commented, minimal, self-contained, reproducible code.
David Winsemius, MD
West Hartford, CT
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