Glitch involving difftime and data frame
On 7 Sep 2004, Peter Dalgaard wrote:
This looks unintentional:
Not so.
d <- as.Date("2004-09-07")
dd <- as.Date("2004-10-04")
data.frame(d,dd,dd-d)
Error in as.data.frame.default(x[[i]], optional = TRUE) :
can't coerce difftime into a data.frame
F <- data.frame(d,dd) F$foo <- dd-d cbind(F,dd-d)
Error in as.data.frame.default(x[[i]], optional = TRUE) :
can't coerce difftime into a data.frame
Basically, the issue is that as.data.frame on a classed object expects
to find a method and there isn't any for difftime...
Difftime depends crucially on attributes on the vector. I wasn't confident that they would be preserved as needed (and I think I had a problem example). Since then we have fixed a lot of the subsetting methods, but even so I am not 100% confident.
Brian D. Ripley, ripley@stats.ox.ac.uk Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595