[R] Converting a 'difftime' to integer - How to???

[Martin Hvidberg]

I want to find the DOY (Day of Year) of some dates. I think to substract the date 1. January from the data to achive this. Something like:

>  d <- as.Date("2006-03-13") - as.Date("2006-01-01") +1
> d
Time difference of 72 days

So far so good. But d is a 'difftime' object. How do I get an Integer value from that?

I tried severel things, incuding the following:

> dd <- as(d,"numeric")
Error in .classEnv(thisClass) : 
  unable to find an environment containing class "difftime"

Sugestions appriciated...

:-) Martin at Hvidberg.net