i try to predict the drought  from the precipitation index of each month for
100 year, from 1985 to 2006

here is my code, i have the

pdsi<-read.csv("pdsi.csv")

pdsi<-ts(pdsi,start=1985,freq=100)

HoltWinters(pdsi)

plot(pdsi)

lines(HoltWinters(pdsi)$fitted,col="red")

pdsi.hw<-HoltWinters(pdsi)

predict(pdsi.hw,n.ahead=48)

plot(pdsi,xlim=c(1985,2006))

lines(predict(pdsi.hw,n.ahead=48),col=2)
my error message is
*Error in xy.coords(x, y) : 'x' and 'y' lengths differ*

** if anyone know please give me advice
*thank in advance*
*jam*

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