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
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