[R] making an inicator variable

[Jennifer Dillon]

Hello,

I am almost a total novice, and I am sure there must be an easy (and 
basic) way to turn a variable of 1's and 2's into a variable of zeros 
and ones.  This is in a data frame, but if I could do it with vectors, 
that's all I need.

Can someone tell me how?

Thanks so much,

Jen