I have an array:
a <- c(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0
The way I cam across this question was when I tried doing something similar where I was defining a function and it was being called with the array like others pointed out
You could do something like this however for this scenarios its less elegant compared to Sven's method.
sapply(a, function(x) afunc(x))
afunc<-function(a){
if (a>0){
a/sum(a)
}
else 1
}