| match.arg {base} | R Documentation |
Argument Verification Using Partial Matching
Description
match.arg matches arg against a table of candidate
values as specified by choices.
Usage
match.arg(arg, choices)
Arguments
arg |
a character string |
choices |
a character vector of candidate values |
Details
In the one-argument form match.arg(arg), the choices are
obtained from a default setting for the formal argument arg of
the function from which match.arg was called.
Matching is done using pmatch, so arg may be
abbreviated.
Value
The unabbreviated version of the unique partial match if there is one; otherwise, an error is signalled.
See Also
pmatch,
match.fun,
match.call.
Examples
## Extends the example for `switch'
center <- function(x, type = c("mean", "median", "trimmed")) {
type <- match.arg(type)
switch(type,
mean = mean(x),
median = median(x),
trimmed = mean(x, trim = .1))
}
x <- rcauchy(10)
center(x, "t") # Works
center(x, "med") # Works
## Not run: center(x, "m") # Error