I'm interested in counting a number of arguments passed to a function. length
can't be used for that purpose:
>> length(2,2,2,2,2)
Error in length(2, 2, 2, 2, 2) :
5 arguments passed to 'length' which requires 1
This is obvious as length
takes 1 argument so:
length(c(2,2,2,2,2))
would produce the desired result - 5.
I want to call my function like that myFunction(arg1, arg2, arg3)
. This can be done with use of an ellipsis:
myCount <- function(...) {length(list(...))}
myCount
would produce the desired result:
>> myCount(2,2,2,2,2)
[1] 5
This is awfully inefficient. I'm calling this function on substantial number of arguments and creating lists just to count number of objects is wasteful. What's the better way of returning the number of arguments passed to a function?
How about
myCount <- function(...) {length(match.call())-1}
This just inspects the passed call (and removes 1 for the function name itself)
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