Trying to figure out For Loops

Question

I'm just trying to get the For loop to increment a rolling window with a 1 month increment and determine the HW parameters at each increment.

ss<-c(29,36,36,48,93,28,35,28,37,50,37,3,25,28,40,45,38,43,34,44,43,25,33,34)
ss2<-t(ss)
for (i in 1:12){
sseries<-ts(ss2[c(i:11+i)],frequency=12)
ssforecasts <- HoltWinters(sseries, beta=FALSE, gamma=FALSE)
ssforecasts
}

But I get :

Error in ts(cbind(xhat = final.fit$level[-len - 1], level = final.fit$level[-len - : 'ts' object must have one or more observations

Try having some `cat` commands in your for loop so that you have a better idea of what is happening and what is causing the error. For example, `for (i in 1:12){ sseries <- ts(ss2[c(i:11+i)],frequency=12) cat(paste0("Information for Series ",i,"\n")) cat(sseries) cat("\n") ssforecasts <- HoltWinters(sseries, beta=FALSE, gamma=FALSE) print(ssforecasts) cat("\n") }` — Kerry Jackson, Sep 05 '18 at 21:09

score 2 · Accepted Answer · answered Sep 05 '18 at 21:11

2

You are calling a slice properly, but R's order of evaluation is not evaluating as you seem to want it to. When you get to i=11 you get this:

> i:11+i
[1] 22

which is what is giving the error, try this instead:

ss<-c(29,36,36,48,93,28,35,28,37,50,37,3,25,28,40,45,38,43,34,44,43,25,33,34)
ss2<-t(ss)
for (i in 1:12){
  sseries<-ts(ss2[c(i:(11+i))],frequency=12)
  ssforecasts <- HoltWinters(sseries, beta=FALSE, gamma=FALSE)
  ssforecasts
}

answered Sep 05 '18 at 21:11

Stedy

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77

It seems to me that the parameters should be printed out, but it wants a continuation. – Angus Sep 05 '18 at 21:57
1

try adding a `print()` statement within the loop – Stedy Sep 05 '18 at 22:15

score 0 · Answer 2 · answered Sep 05 '18 at 22:15

0

OK, I had to use the statement print(ssforecasts) to get the results.

answered Sep 05 '18 at 22:15

Angus

355
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12

Trying to figure out For Loops

2 Answers2