if else in R

Hi,

This would be an issue with if() as well as if/else.  ab$b has 4
numbers in it, so ab$b > 0 evaluates to "TRUE TRUE FALSE TRUE" or
whatever. if() can only take a single true or false. Cheers! Nick

On Tue, Nov 19, 2013 at 8:30 PM, Gary Dong <pdxgary163 at gmail.com>
wrote:

Dear R users,

I am a R beginner and I am having trouble in using "If Else" in R.

Here is

an example:

## create a data frame

a<-c(1,2,3,4)
b<-c(2,0,5,0)
ab<-data.frame(cbind(a,b))

##calculate c, which is the ratio between a and b

if(ab$b>0) {
 ab$c<-ab$a/ab$b
} else {
 ab$c<-0
 }

here is the error I got:

Warning message:
In if (ab$b > 0) { :
  the condition has length > 1 and only the first element will be

used.

Any help is appreciated!

Gary

        [[alternative HTML version deleted]]