[R] removing observations

[Justin G. Gardner]

Hello R list.

I am sure this is an easy question, please forgive my 
ignorance of R.


I have a panel data set (25 years) and I would like to break 
it up by year, and run a few tests.  How is this done in R?  
In STATA it is quite simple (keep if year =1970).  If someone 
could give me an example of how to do it for a single year I 
am sure I could make a little loop to do it for all 25.

Thanks,
JGG.