[R] factor always have type integer

[Roger D. Peng]

In some cases it makes sense to store "character" variables as factors 
(integers with labels) since this can take up much less memory.  If 
you really want to store `v2' as character, just do

data.frame(v1, I(v2))

-roger

Erich Neuwirth wrote:
> typeof applied to a factor always seems to return "integer",
> independently of the type of the levels.
> This has a strange side effect.
> When a variable is "imported" into a data frame,
> its type changes.
> character variables automatically are converted
> to factors when imported into data frames.
> 
> Here is an example:
> 
>  > v1<-1:3
>  > v2<-c("a","b","c")
>  > df<-data.frame(v1,v2)
>  > typeof(v2)
> [1] "character"
>  > typeof(df$v2)
> [1] "integer"
> 
> It is somewhat surprising that
> the types of v2 and df$v2 are different.
> 
> the answer is to do
> levels(df$v2)[df$v2]
> but that is somewhat involved.
> 
> Should the types not be identical, and typeof applied to factors
> return the type of the levels?
> 
>