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

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