[R] No years() function?

[Sérgio Nunes]

Hi,

I'm trying to aggregate date values using the aggregate function. For example:

aggregate(data,by=list(weekdays(LM),months(LM)),FUN=length)

I would also like to aggregate by year but there seems to be no
years() function.
Should there be one? Is there any alternative choice?

Also, a hours() function would be great. Any tip on this?

Thanks in advance!
Sérgio Nunes