[R] ?bug? strange factors produced by chron

[Petr Pikal]

Hallo all

Please help me. I am lost and do not know what is the problem. I have 
a factor called kvartaly.

> attributes(kvartaly)
$levels
[1] "1Q.04" "2Q.04" "3Q.04" "4Q.04" "1Q.05" "2Q.05" "3Q.05" "4Q.05"
$class
[1] "factor"
> mode(kvartaly)
[1] "numeric"
> str(kvartaly)
 Factor w/ 8 levels "1Q.04","2Q.04",..: 1 1 1 1 1 1 1 1 1 1 ...
>

but if I call split it throws an error

> split(rnorm(731),kvartaly)
Error in split(x, f) : second argument must be a factor

so I tried to make a test example which works if I try to construct 
factor manually but fails if I use chron

vec<-c("1Q.04", "1Q.05", "1Q.06")
fac<-as.factor(rep(vec,c(5,5,5)))

split(rnorm(15),fac)
$"1Q.04"
[1]  1.9803999 -0.3672215 -1.0441346  0.5697196 -0.1350546

$"1Q.05"
[1]  2.40161776 -0.03924000  0.68973936  0.02800216 -0.74327321

$"1Q.06"
[1]  0.1887923 -1.8049586  1.4655549  0.1532533  2.1726117

vec1<-as.Date(Sys.time())
vec1<-c(vec1, vec1-100, vec1-300)
vec1<-rep(vec1,c(5,5,5))
fac1<-interaction(quarters(as.chron(as.POSIXct(vec1))), 
format(vec1,"%y"))
> split(rnorm(15),fac1)
Error in split(x, f) : second argument must be a factor
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Why split does not accept fac1 if according to all tests it **is** a 
factor?

Thank you
Petr

Petr Pikal
petr.pikal at precheza.cz