[R] add a legend to a periodogram

[David Winsemius]

On Aug 31, 2011, at 12:06 PM, Peter Maclean wrote:

> Hi:
> Trying for hours to add a legend to a periodogram. Any help will be  
> appreciated.
> For example, how can I add a legent (showing x1, x2, x3, x4) to both  
> plots (generated by spec.program() and plot()? Here is a worked  
> example.
>
> require(TSA)
> require(graphics)
> require(stats)
> t<-1986:2011
> x1<-cos(t*1990/2011)
> x2<-cos(t*2000/20011)
> x3<-sin(t*1990/2011)
> x4<-sin(t*2000/2011)
> y<-cbind(t,x1,x2, x3,x4)
> y.time = ts(y.time, start=1986, frequency=1)
> y.spc<-spec.pgram(y.time, spans = c(3,3),  
> detrend=FALSE,log="no",plot = TRUE, kernel("modified.daniell",  
> c(5,7)))
> plot(y.spc, plot.type = "marginal", main="Smoothed Periodogram")

The code throws an error. Perhaps you meant:


> y.time = ts(y[ ,"t"], start=1986, frequency=1)

At any rate the answer to the question is probably:

class(y.spc)  # class "spec"
?methods(plot) # the spec method is not hidden
plot.spec   # uses base graphics ..... so

?legend



>
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David Winsemius, MD
West Hartford, CT