R count function calls

问题:

This should be easy, but can't find any straight-forward answers on google or SO.

Imagine in R I run a function FOuter(), and within its body, it does some loop and calls another function FInner(). Is there a simple way of counting/recording the number of times FInner gets called? I'm trying to estimate how much time I can save if I optimize FInner.

回答1:

You're looking for trace.

f1 <- function() 1
f2 <- function() {
    for(i in 1:10) f1()
}

.count <- 0
trace(f1, tracer=function() .count <<- .count +1)
f2()
.count
# 10
untrace(f1)