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Variable Length Differ

2 messages · TJUN KIAT TEO, Jeff Newmiller

Original
TJUN KIAT TEO
# 
This is my code

    BSUPred<-(forecast(BSU,h=h)[[2]])
    PressurePred<-(forecast(Pressure,h=h)[[2]])
    Placer<-(rep(1,h))
    test<-as.data.frame(cbind(BSUPred,PressurePred))
    test$Placer<-rep(1:2,h/12)
    test$Placer<-i
    test<-as.data.frame((test[c("Placer","BSUPred","PressurePred")]))
    resp<-predict(fit,newdata=test,type="response")
    Pred<-ifelse((predict(fit,newdata=test,type="response")>0.5),1,0)

But I get this error message

Error in model.frame.default(Terms, newdata, na.action = na.action, xlev = object$xlevels) : 
  variable lengths differ (found for 'Placer') 

Can anyone help?

Thanks

Tjun Kiat
Jeff Newmiller
# 
This is not reproducible (see for example [1]), so it is very difficult to know exactly what the problem is. Also, you need to post on this list using the plain text format option in your email software, since the HTML format you used can mess up your code.

I can say that using "[" indexing on a data frame will give you back a data frame as long as you have multiple result columns, and cbind converts that to a matrix. Since data frames typically have columns of a variety of types ("storage modes") while matrices do not, you are likely damaging your data frames every time you use cbind. I recommend that you interactively execute (e.g. using copy/paste) one line at a time in your script and use the str() function after each line to learn the structure of the the objects you are creating and modifying. 

The best way to make a data frame from vector is:

test <- data.frame( BSUPred, PressurePred )

or

test <- data.frame( BSUPred=BSUPred, PressurePred=PressurePred )

A couple of ways to add columns to data frames that don't damage the data frame are:

test$Placer <- i

or (an example where specifying only one column identifies a vector rather than the usual data frame result)

test[ , "Placer" ] <- i

or even (not recommended for efficiency reasons):

test <- data.frame( test, Placer=i )

If this is not enough help, make your example reproducible using the advice in [1] and try posting again.

[1] http://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example
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On November 2, 2014 3:19:45 AM PST, TJUN KIAT TEO <teotjunk at hotmail.com> wrote: