| match.arg {base} | R Documentation |
match.arg matches arg against a table of candidate
values as specified by choices.
match.arg(arg, choices, several.ok = FALSE)
arg |
a character string |
choices |
a character vector of candidate values |
several.ok |
logical specifying if arg should be allowed
to have more than one element. |
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 if several.ok is false, as per
default. When several.ok is true and there is more than one
match, all unabbreviated versions of matches are returned.
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
## Allowing more than one match:
match.arg(c("gauss", "rect", "ep"),
c("gaussian", "epanechnikov", "rectangular", "triangular"),
several.ok = TRUE)