R: Examples for 'base::match.arg'

### ** Examples

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

[1] -0.2019009

center(x, "med")     # Works

[1] -0.1539195

try(center(x, "m"))  # Error

Error in match.arg(type) : 
  'arg' should be one of "mean", "median", "trimmed"

stopifnot(identical(center(x),       center(x, "mean")),
          identical(center(x, NULL), center(x, "mean")) )

## Allowing more than one 'arg' and hence more than one match:
match.arg(c("gauss", "rect", "ep"),
          c("gaussian", "epanechnikov", "rectangular", "triangular"),
          several.ok = TRUE)

[1] "gaussian"     "rectangular"  "epanechnikov"

match.arg(c("a", ""),  c("", NA, "bb", "abc"), several.ok=TRUE) # |-->  "abc"

[1] "abc"

Examples for 'base::match.arg'

Argument Verification Using Partial Matching