[R] factor to numeric in data.frame
Heinz Tuechler
tuechler at gmx.at
Sat Apr 2 13:01:57 CEST 2005
Dear All,
Assume I have a data.frame that contains also factors and I would like to
get another data.frame containing the factors as numeric vectors, to apply
functions like sapply(..., median) on them.
I read the warning concerning as.numeric or unclass, but in my case this
makes sense, because the factor levels are properly ordered.
I can do it, if I write for each single column "unclass(...), but I would
like to use indexing, e.g. unclass(df[1:10]).
Is that possible?
Thanks,
Heinz Tüchler
## Example:
f1 <- factor(c(rep('c1-low',2),rep('c2-med',5),rep('c3-high',3)))
f2 <- factor(c(rep('c1-low',5),rep('c2-low',3),rep('c3-low',2)))
df.f12 <- data.frame(f1,f2) # data.frame containing factors
## this does work
df.f12.num <- data.frame(unclass(df.f12[[1]]),unclass(df.f12[[2]]))
df.f12.num
## this does not work
df.f12.num <- data.frame(unclass(df.f12[[1:2]]))
df.f12.num
## this does not work
df.f12.num <- data.frame(unclass(df.f12[1:2]))
df.f12.num
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