[R] ipred and lda

[Uwe Ligges]

Stefan Böhringer wrote:

> Dear all,
> 
> can anybody help me with the program below? The function predict.lda
> seems to be defined but cannot be used by errortest.
> 
> The R version is 1.7.1


R-1.8.1 is recent.

predict.lda() is hidden in a namespace, so you cannot access it that 
way. Please use the generic (predict(), which calls the method) rather 
than calling methods directly.

However, predict.lda() won't work in errorest() (not errortest, BTW) as is.

Use an own function like mypredict.lda() which looks like:
   mypredict.lda <- function(object, newdata)
     predict(object, newdata = newdata)$class
which is given in the examples of ?errorest.

Uwe Ligges





> Thanks in advance,
> 
> 	Stefan
> 
> ----------------
> library("MASS");
> library("ipred");
> 
> data(iris3);
> tr <- sample(1:50, 25);
> train <- rbind(iris3[tr,,1], iris3[tr,,2], iris3[tr,,3]);
> test <- rbind(iris3[-tr,,1], iris3[-tr,,2], iris3[-tr,,3]);
> cl <- factor(c(rep("s",25), rep("c",25), rep("v",25)));
> z <- lda(train, cl);
> predict(z, test)$class;
> 
> data.frame(class=cl, train);
> flowers <- data.frame(class=cl, train);
> errorest(class ~ ., data=flowers, model=lda, estimator="cv",
> predict=predict.lda);
> 
> Error-Message is :
> Error: Object "predict.lda" not found
> 
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