Have you received a reply to this post? I haven't seen one.
> t9 <- 9:10
> class(t9) <- "Date"
> t9
[1] "1970-01-10" "1970-01-11"
> as.factor(t9)
[1] 9 10
Levels: 9 10
I confirmed what you got with a slightly different example:
> t9 <- 9:10
> class(t9) <- "Date"
> t9
[1] "1970-01-10" "1970-01-11"
# Apparently, 'class(times) <- "Date"' had the anticipated effect
As you indicated, 'as.factor' in R-2.2.1 used character string
representations of the dates as levels, while in R-2.3.0 it did not:
> as.factor(t9) # in R-2.3.0
[1] 9 10
Levels: 9 10
> as.factor(t9) # in R-2.2.1
[1] 1970-01-10 1970-01-11
Levels: 1970-01-10 1970-01-11
R-2.2.1 and R-2.3.0 returned the same for the following:
> as.numeric(as.factor(t9))
[1] 1 2
> sessionInfo()
Version 2.3.0 (2006-04-24)
i386-pc-mingw32
attached base packages:
[1] "grid" "methods" "stats" "graphics" "grDevices" "utils"
[7] "datasets" "base"
other attached packages:
tseries zoo quadprog lattice
"0.10-0" "1.0-6" "1.4-8" "0.13-8"
> sessionInfo()
Version 2.3.0 (2006-04-24)
i386-pc-mingw32
attached base packages:
[1] "grid" "methods" "stats" "graphics" "grDevices" "utils"
[7] "datasets" "base"
other attached packages:
tseries zoo quadprog lattice
"0.10-0" "1.0-6" "1.4-8" "0.13-8"
hope this helps.
spencer graves
Antonio, Fabio Di Narzo wrote:
> Dear all,
> I have noticed a little change in the behaviour of as.factor from R-2.2.1 to
> R-2.3.0, and can't find it in the NEWS.
>
> In R-2.3.0:
>
>>times <- 1:5
>>class(times) <- "Date"
>>as.factor(times)
>
> [1] 1 2 3 4 5
> Levels: 1 2 3 4 5
>
> In R-2.2.1:
>
>>as.factor(times)
>
> [1] 1970-01-02 1970-01-03 1970-01-04 1970-01-05 1970-01-06
> Levels: 1970-01-02 1970-01-03 1970-01-04 1970-01-05 1970-01-06
>
> Is this the intended behaviour?
> Note that the change is reflected on other functions which seems to use
> as.factor internally, for example 'tapply'.
> Consider the following code:
>
> times <- 1:5
> class(times) <- "Date"
> id <- rep(times, each=2)
> vals <- rep(1:2,5)
> tapply(vals, id, mean)
>
> Under R-2.2.1 this gives:
> 1970-01-02 1970-01-03 1970-01-04 1970-01-05 1970-01-06
> 1.5 1.5 1.5 1.5 1.5
>
> But under R-2.3.0 the output is:
> 1 2 3 4 5
> 1.5 1.5 1.5 1.5 1.5
>
> Antonio, Fabio Di Narzo.
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
> R-devel@r-project.org mailing list
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