Hello Andy,
thanks for your answer and sorry that I did not check the rfNews.
You are right, presently I am only looking at variable importance and
therefore I am very happy to hear that I won`t have problems using
ordered factors.
Since I just started to fiddle around with randomForest it might be
that I will have some more questions later - let`see.
But presently I am very grateful that you provide this package.
Greets
Birgit
Am 29.04.2008 um 16:29 schrieb Liaw, Andy:
If you are using the latest version (4.5-25), you will see in rfNews
() that that's the problem I need to fix. The package was able to
handle ordered factors, but some more stringent checks for factor
levels consistency introduced in 4.5-23 broke the support for
ordered factors in prediction.
From the code you've shown, it looks like you are just growing the
forest to evaluate variable importance or other things, instead of
predicting other data (since you set keep.forest=FALSE). If
that's the case, you should be fine, as the problem only happens
when you try to call predict() with models that contain ordered
factors as predictors.
(Ordered factors are basically treated as numerics in RF: trees
only make use of ranks for numeric variables, so there's basically
no difference between ordered factors and numeric variables as
predictors.)
Andy
From: Birgit Lemcke
Hello R-user!
I am running R 2.7.0 on a Power Book (Tiger). (I am still R and
statistics beginner)
I try to find the most important variables to divide my dataset as
given in a categorical variable.
code:
Test.rf4<-randomForest(Sex~.,na.action=na.roughfix, data=Subset4,
importance=TRUE, proximity=TRUE, ntree=10000, do.trace=1000,
keep.forest=FALSE)
My dataset contains also ordered factors classified as such.
Is randomForest able to deal with it, does it change anything or is
there no difference in using factors or ordered factors?
Many thanks in advance
B.
Birgit Lemcke
Institut für Systematische Botanik
Zollikerstrasse 107
CH-8008 Zürich
Switzerland
Ph: +41 (0)44 634 8351
[EMAIL PROTECTED]
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Switzerland
Ph: +41 (0)44 634 8351
[EMAIL PROTECTED]
175 Jahre UZH
«staunen.erleben.begreifen. Naturwissenschaft zum Anfassen.»
MNF-Jubiläumsevent für gross und klein.
19. April 2008, 10.00 Uhr bis 02.00 Uhr
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Weitere Informationen http://www.175jahre.uzh.ch/naturwissenschaft
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