| match.fun {base} | R Documentation |
Function Verification for “Function Variables”
Description
Matches FUN to a function, where FUN can be a
character (string), e.g., "*" or "fred",
or a function such as pmax.
Returns an error if no matching function is found.
Usage
match.fun(FUN, descend=TRUE)
Arguments
FUN |
function, e.g. as passed to |
descend |
logical; control whether to search under non-function objects. |
Details
If descend=TRUE, match.fun will look underneath
non-function objects with the given name; otherwise if FUN
points to a non-function object then an error is generated.
This is now used in base functions such as
apply, lapply, outer,
sweep, and the like.
Value
A function matching FUN or an error is generated.
Bug/Feature
A character argument to FUN is always matched to a
function, even if there is a non-function object higher up the
search list with the same name.
Author(s)
Jonathan Rougier
See Also
match.arg
Examples
# Same as get("*"):
match.fun("*")
# Overwrite outer with a vector
outer <- 1:5
## Not run:
match.fun(outer, descend = FALSE) #-> Error: not a function
## End(Not run)
match.fun(outer) # finds it anyway
is.function(match.fun("outer")) # as well