I have a problem with ellipsis when I use optional arguments in my function definition. To clarify, I define following functions:
func1 <- function (x) (x-2)^2
func3 <- function (fun, arg.curve.user){
arg.curve.user$expr <- substitute(func1)
arg.curve.default <- list(col = "blue", n = 1000, main = "This is a test")
arg.curve <- modifyList (arg.curve.default, arg.curve.user)
do.call("curve", arg.curve)
}
# optimizes func1 and call func2 to plot func1
func2 <- function (lb, ub, n.restarts = 5, n.sim = 10, ...){
arg.curve.user <- as.list(substitute(list(...)))
output <- gosolnp(fun = func1, LB = lb, UB = ub, n.restarts = n.restarts,
n.sim = n.sim)$par
func3(fun = func1, arg.curve.user = arg.curve.user)
return(output)
}
By calling func2, func1 is optimized and also plotted through a func3 call (package Rsolnp is required).
func2 ( lb = 0, ub = 8, n.restarts = 5, n.sim = 10, n = 200, from = 0, to = 8)
But suppose a user misspells n.restarts and writes nrestarts:
func2 ( lb = 0, ub = 8, nrestarts = 5, n.sim = 10, n = 200, from = 0, to = 8)
In this case, I expects R to implement the following plans to deal with absence of n.restarts:
But this does not happen and R assigns value of n (200) to n.restarts instead!!
Can anyone help me to fix this problem?
Many thanks
It is partial matching the n argument to n.restarts when one is not supplied by the user. Instead, and contrary to the advice of @Andrie (which will work, of course), there is a mechanism that allows you to continue in the manner you have with an argument n and and argument n.restarts. The trick is to place arguments you want to match exactly after the ....
func2 <- function (lb, ub, ..., n.restarts = 5, n.sim = 10){
writeLines(paste("Value of `n.restarts` is", n.restarts))
arg.curve.user <- as.list(substitute(list(...)))
output <- gosolnp(fun = func1, LB = lb, UB = ub, n.restarts = n.restarts,
n.sim = n.sim)$par
func3(fun = func1, arg.curve.user = arg.curve.user)
output
}
In use this gives:
> func2 (lb = 0, ub = 8, n.restarts = 2, n.sim = 10, n = 200,
+ from = 0, to = 8)
Value of `n.restarts` is 2 <---- Here!
Iter: 1 fn: 6.926e-15 Pars: 2.00000
Iter: 2 fn: 2.501e-15 Pars: 2.00000
solnp--> Completed in 2 iterations
Iter: 1 fn: 8.336e-16 Pars: 2.00000
Iter: 2 fn: 8.336e-16 Pars: 2.00000
solnp--> Completed in 2 iterations
[1] 2
> func2 (lb = 0, ub = 8, nrestarts = 2, n.sim = 10, n = 200,
+ from = 0, to = 8)
Value of `n.restarts` is 5 <---- Here! Default
Iter: 1 fn: 2.83e-15 Pars: 2.00000
Iter: 2 fn: 2.5e-15 Pars: 2.00000
solnp--> Completed in 2 iterations
Iter: 1 fn: 2.037e-15 Pars: 2.00000
Iter: 2 fn: 2.037e-15 Pars: 2.00000
solnp--> Completed in 2 iterations
Iter: 1 fn: 1.087e-15 Pars: 2.00000
Iter: 2 fn: 1.087e-15 Pars: 2.00000
solnp--> Completed in 2 iterations
Iter: 1 fn: 8.558e-16 Pars: 2.00000
Iter: 2 fn: 8.558e-16 Pars: 2.00000
solnp--> Completed in 2 iterations
Iter: 1 fn: 7.147e-16 Pars: 2.00000
Iter: 2 fn: 7.147e-16 Pars: 2.00000
solnp--> Completed in 2 iterations
[1] 2
Warning messages:
1: In plot.window(...) : "nrestarts" is not a graphical parameter
2: In plot.xy(xy, type, ...) : "nrestarts" is not a graphical parameter
3: In axis(side = side, at = at, labels = labels, ...) :
"nrestarts" is not a graphical parameter
4: In axis(side = side, at = at, labels = labels, ...) :
"nrestarts" is not a graphical parameter
5: In box(...) : "nrestarts" is not a graphical parameter
6: In title(...) : "nrestarts" is not a graphical parameter