Sorry for my bad description, i don't want get a constructed algorithm without own work. i only hoped to get some advice how to do this. i don't want to predict any sort of data, i reference only to newdata which variables are the same as in the model data. But if factors in the data than i can by possibly that the newdata has a level which doesn't exist in the original data. So i have to compare each factor in the data and in the newdata and if the newdata has a levels which is not in the original data and drop this variable and do compute the model and prediction again. I thought this problem is quite common and i can use an algorithm somebody has already implemented.
best regards Andreas -------- Original-Nachricht -------- > Datum: Wed, 25 Nov 2009 00:48:59 -0500 > Von: David Winsemius <dwinsem...@comcast.net> > An: Andreas Wittmann <andreas_wittm...@gmx.de> > CC: r-help@r-project.org > Betreff: Re: [R] predict: remove columns with new levels automatically > > On Nov 24, 2009, at 2:24 PM, Andreas Wittmann wrote: > > > Dear R-users, > > > > in the follwing thread > > > > http://tolstoy.newcastle.edu.au/R/help/03b/3322.html > > > > the problem how to remove rows for predict that contain levels which > > are not in the model. > > > > now i try to do this the other way round and want to remove columns > > (variables) in the model which will be later problematic with new > > levels for prediction. > > > > ## example: > > set.seed(0) > > x <- rnorm(9) > > y <- x + rnorm(9) > > > > training <- data.frame(x=x, y=y, z=c(rep("A", 3), rep("B", 3), > > rep("C", 3))) > > test <- data.frame(x=t<-rnorm(1), y=t+rnorm(1), z="D") > > > > lm1 <- lm(x ~ ., data=training) > > ## prediction does not work because the variable z has the new level > > "D" > > predict(lm1, test) > > > > ## solution: the variable z is removed from the model > > ## the prediction happens without using the information of variable z > > lm2 <- lm(x ~ y, data=training) > > predict(lm2, test) > > > > How can i autmatically recognice this and calculate according to this? > > Let me get this straight. You want us to predict in advance (or more > accurately design an algorithm that can see into the future and work > around) any sort of newdata you might later construct???? > > -- > > David Winsemius, MD > Heritage Laboratories > West Hartford, CT -- Preisknaller: GMX DSL Flatrate für nur 16,99 Euro/mtl.! http://portal.gmx.net/de/go/dsl02 ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
