Addition involving numeric(0) values

Question

Suppose x is a real number, or a vector. i is valued-False. Then x[i] will return numeric(0). I would like to treat this as a real number 0, or integer 0, which are both fit for

Answer 1

It is only when we do the +, it is a problem. This can be avoided if we use sum

sum(numeric(0), 5)
#[1] 5
sum(numeric(0), 5, 10)
#[1] 15

Or if we need to use +, an easy option is to concatenate with 0, select the first element. If the element is numeric(0), that gets replaced by 0, for other cases, the first element remain intact

c(numeric(0), 0)[1]
#[1] 0

Using a small example

lst1 <- list(1, 3, numeric(0),  4, numeric(0))
out <- 0
for(i in seq_along(lst1)) {
       out <- out + c(lst1[[i]], 0)[1]
  }

out
#[1] 8