[R] how to recode with an if-type statement

[Casey Klofstad]

I'm sure this is easy, but I'm having a hard time figuring out how to
recode some data in R.

I have a variable "numpeers" which is valued 1, 2, or 3. I also have
three other variables called "w9zd9_1," "w9zd9_2," and "w9zd9_3." I
want to use these variables to create a new item called "distot."

Specifically, here is what I want to do:

-if numpeers=1, then distot=w9zd9_1

-if numpeers=2, then distot=(w9zd9_1 + w9zd9_2)/2

-if numpeers=3, then distot=(w9zd9_1 + w9zd9_2 + w9zd9_3)/3

Thanks, in advance, for the help!

-- 
Casey A. Klofstad
University of Miami
Department of Political Science
Coral Gables, FL

klofstad at gmail.com
http://www.as.miami.edu/personal/cklofstad/