Double sum computation in R

Question

I'm having problem writing the following double sum into a function in r:

where the I function is an indicator function and we have n observations x_1...x_n.

I tried something like this

sum( (x <= t) / (sum((x<=x)))^2)

Answer 1

You can do:

sumiI <- function(xi, x) sum(xi<=x)
sum(1/sapply(x[x<=t], FUN=sumI, x=x))