Let's say I have a function like this:
myFun <- function(arg1, arg2, arg3) {
if(arg3 == 'A') funA(arg1, arg2)
else if(arg3 == 'B') funB(arg1, arg2)
else if(arg3 == 'C') funC(arg1, arg2)
}
Is there a way to not continually repeat arg1, arg2, but somehow construct the call more intelligently? I was looking into match.call but am not sure if it fits my use case.
You could use match.arg() along with paste0().
myFun <- function(arg1, arg2, arg3) {
stopifnot(arg3 %in% c("A", "B", "C"))
paste0("fun", arg3)
}
This will trigger an error if arg3 is not in the choices c("A", "B", "C")
myFun(arg3 = "A")
# [1] "funA"
myFun(arg3 = "defg")
# Error: arg3 %in% c("A", "B", "C") is not TRUE
So we can just use that in do.call() to call it with the other arguments.
myFun <- function(arg1, arg2, arg3) {
stopifnot(arg3 %in% c("A", "B", "C"))
do.call(paste0("fun", arg3), list(arg1, arg2))
}
Can your functions actually be pasted together or is that just an effect of the example? If so, consider this:
get(paste0("me", "an"))(1:5)
[1] 3
I created the function by pasting its name together. So in your example:
myFun <- function(arg1, arg2, arg3) {
get(paste0("fun", arg3))(arg1, arg2)
}
Here is an alternative approach using switch
myFun <- function(arg1, arg2, arg3){
switch(arg3,
A = {
out <- funA(arg1, arg2)
},
B = {
out <- funB(arg1, arg2)
},
C= {
out <- funC(arg1, arg2)
},
stop("Enter something that makes sense!")
)
return(out)
}
funA <- function(x,y) mean(c(x,y))
funB <- function(x,y) sum(c(x,y))
funC <- function(x,y) var(c(x,y))
myFun(3, 4, "A")
#[1] 3.5
myFun(3, 4, "B")
#[1] 7
myFun(3, 4, "C")
#[1] 0.5
myFun(3, 4, "D")
Error in myFun(3, 4, "D") : Enter something that makes sense!
myFun <- function(arg1, arg2, arg3) get(paste0("fun", arg3))(arg1, arg2)but I'm not sure whether your functions connect as in your example.