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I have a function defined as
myFun <- function(x, y, ...) { # using exists if (exists("z")) { print("exists z!") } # using missing try(if (!missing("z")) { print("z is not missing!") }, silent = TRUE) # using get try(if (get("z")) { print("get z!") }, silent = TRUE) # anotherFun(...) } In this function, I want to check whether user input "z" in the argument list. How can I do that? I tried exists("z"), missing("z"), and get("z") and none of them works.
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Get the List of Arguments of a Function in R Programming – args() Function. args() function in R Language is used to get the required arguments by a function. It takes function name as arguments and returns the arguments that are required by that function.
Functions are defined using the function() directive and are stored as R objects just like anything else. In particular, they are R objects of class “function”. Here's a simple function that takes no arguments and does nothing.
An R function is a packaged recipe that converts one or more inputs (called arguments) into a single output. The recipe is implemented as a single R expression that uses the values of the arguments to compute the result.
Arguments are the parameters provided to a function to perform operations in a programming language. In R programming, we can use as many arguments as we want and are separated by a comma. There is no limit on the number of arguments in a function in R.
I think you're simply looking for hasArg
myFun <- function(x, y, ...) { hasArg(z) } > myFun(x=3, z=NULL) [1] TRUE From ?hasArg:
The expression hasArg(x), for example, is similar to !missing(x), with two exceptions. First, hasArg will look for an argument named x in the call if x is not a formal argument to the calling function, but ... is. Second, hasArg never generates an error if given a name as an argument, whereas missing(x) generates an error if x is not a formal argument.
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