[R] Keep value lables with data frame manipulation

[Jol, Arne]

Dear R,

I import data from spss into a R data.frame. On this rawdata I do some
data processing (selection of observations, normalization, recoding of
variables etc..). The result is stored in a new data.frame, however, in
this new data.frame the value labels are lost.

Example of what I do in code:

# read raw data from spss
rawdata <- read.spss("./data/T50937.SAV",
	use.value.labels=FALSE,to.data.frame=TRUE)

# select the observations that we need
diarydata <- rawdata[rawdata$D22==2 | rawdata$D22==3 | rawdata$D22==17 |
rawdata$D22==18 | rawdata$D22==20 | rawdata$D22==22 |
 			rawdata$D22==24 | rawdata$D22==33,]

The result is that rawdata$D22 has value labels and that diarydata$D22
is numeric without value labels.

Question: How can I prevent this from happening?

Thanks in advance!
Groeten,
Arne