[R] any r package can handle factor levels not in the test set

Richard M. Heiberger rmh at temple.edu
Tue Jan 13 03:08:46 CET 2015

You need to define the levels of the training set to include all
levels that you might see.
Something like this

> A <- factor(letters[1:5])
> B <- factor(letters[c(1,3,5,7,9)])
> A
[1] a b c d e
Levels: a b c d e
> B
[1] a c e g i
Levels: a c e g i
> training <- factor(A, levels=unique(c(levels(A), levels(B))))
> training
[1] a b c d e
Levels: a b c d e g i

In the future please "provide commented, minimal, self-contained,
reproducible code."

On Mon, Jan 12, 2015 at 9:00 PM, HelponR <suncertain at gmail.com> wrote:
> It looks like gbm, glm all has this issue
> I wonder if any R package is immune of this?
> In reality, it is very normal that test data has data unseen in training
> data. It looks like I have to give up R?
> Thanks!
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> and provide commented, minimal, self-contained, reproducible code.

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