match.arg {base} | R Documentation |
match.arg
matches arg
against a table of candidate
values as specified by choices
.
match.arg(arg) 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
.
## 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 center(x, "m") # Error