| match.arg {base} | R Documentation |
match.arg matches arg against a table of candidate
values as specified by choices.
match.arg(arg, choices)
arg |
a character string |
choices |
a character vector of candidate values |
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.
The unabbreviated version of the unique partial match if there is one; otherwise, an error is signalled.
pmatch,
match.fun,
match.call.
require(stats)
## 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
try(center(x, "m")) # Error