function {base}R Documentation

Function Definition

Description

These functions provide the base mechanisms for defining new functions in the R language.

Usage

function( arglist ) expr
return(value)

Arguments

arglist Empty or one or more name or name=expression terms.
value An expression.

Details

In R (unlike S) the names in an argument list cannot be quoted non-standard names.

If value is missing, NULL is returned. If it is a single expression, the value of the evaluated expression is returned.

If the end of a function is reached without calling return, the value of the last evaluated expression is returned.

Warning

Prior to R 1.8.0, value could be a series of non-empty expressions separated by commas. In that case the value returned is a list of the evaluated expressions, with names set to the expressions where these are the names of R objects. That is, a=foo() names the list component a and gives it value the result of evaluating foo().

This has been deprecated (and a warning is given), as it was never documented in S, and whether or not the list is named differs by S versions.

References

Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.

See Also

args and body for accessing the arguments and body of a function.

debug for debugging; invisible for return(.)ing invisibly.

Examples

norm <- function(x) sqrt(x%*%x)
norm(1:4)

## An anonymous function:
(function(x,y){ z <- x^2 + y^2; x+y+z })(0:7, 1)

[Package base version 2.1.0 Index]