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specifying arguments in functions and calling functions, within functions

Rui Barradas 
Hello,

You define a 2nd version of Scale with the dots argument but do not use it.


Scale2 <- function(x, method=c("mean", "median"),...) {
    scl <- match.fun(method)
    scl(x, ...)   # Here!
}

Scale2(ex, method=median, na.rm=TRUE)  # both return
Scale2(ex, method="median", na.rm=TRUE)  # the median

You could also use 'na.rm = TRUE' instead of '...', since both mean and 
median use it. Anyway, if you define a function with certain arguments, 
do try to use them in the function body. :)

As for the method argument, when the default value is a vector, it's 
primary use is to check that one of those vector values and _only_ one 
of those is passed to the function. More or less like this.

Scale3 <- function(x, method=c("mean", "median"),...) {
    method <- match.arg(method)
    scl <- match.fun(method)
    scl(x, ...)
}

Scale3(ex, method=median, na.rm=TRUE)  # Error
Scale3(ex, method="median", na.rm=TRUE)  # Right
Scale3(ex, method="var", na.rm=TRUE)  # Other type of error


Hope this helps,

Rui Barradas

Em 26-09-2012 16:56, K. Brand escreveu:

Thread (5 messages)

K. Brand specifying arguments in functions and calling functions, within functions Sep 26 Sarah Goslee specifying arguments in functions and calling functions, within functions Sep 26 Rui Barradas specifying arguments in functions and calling functions, within functions Sep 26 David L Carlson specifying arguments in functions and calling functions, within functions Sep 26 K. Brand specifying arguments in functions and calling functions, within functions Sep 27