How to call a function in R which I specify via the commandline? -

how do in r:

i have sourced function name examplefoo suppose:

examplefoo <- function(a, predefined, signature)

given character vector examplefoo, how can use call function name?

it depends if going on inside function or @ top level. i'll take in reverse order.

examplefoo <- function(a, predefined, signature) {    1:10 }  fun <- "examplefoo"  get(fun) get(fun)()  > get(fun) function(a, predefined, signature) {    1:10 } > get(fun)()  [1]  1  2  3  4  5  6  7  8  9 10 

in function, match.fun argument applicable here. get looks objects name supplied it, whereas match.fun considers function objects when searching. has additional benefit of not matching non-function objects may have same name.

foo <- function(f) {   bar <- match.fun(f)   bar() }  > foo(fun)  [1]  1  2  3  4  5  6  7  8  9 10 > foo("examplefoo")  [1]  1  2  3  4  5  6  7  8  9 10 

you can't use match.fun (easily?) @ top level designed perform matching in parent frame of caller , global environment doesn't have parent (iirc).

other examples

@agstudy suggests switch based approach having wrapper function can call 1 of several pre-defined functions name. in comments there proposed 2 simpler alternatives. here expand upon that:

foo1 <- function(method, ...) {   dots <- list(...)   fun <- match.fun(method)   do.call(fun, dots) }  

or

foo2 <- function(method = c("fun1", "fun2", "fun3"), ...) {   dots <- list(...)   method <- match.arg(method)   fun <- match.fun(method)   do.call(fun, dots) } 

i've written these pretty general functions take arguments plus method. if functions reference / passed method have ... argument, these called directly, perhaps 1 or more named arguments, e.g.

## assuming `method` refers function first argument `x` , ##   `...` argument foo3 <- function(method, x, ...) {   fun <- match.fun(method)   fun(x, ...) }