Are we using R, rather than S?

Description

Test if running under R.

Usage

is.R()

Details

The function has been written such as to correctly run in all versions of R, S and S-PLUS. In order for code to be runnable in both R and S dialects, your code must either define is.R or use it as

if (exists("is.R") && is.function(is.R) && is.R()) {
## R-specific code
} else {
## S-version of code
}

Value

is.R returns TRUE if we are using R and FALSE otherwise.

See Also

R.version, system.

Examples

x <- runif(20); small <- x < 0.4
## 'which()' only exists in R:
if(is.R()) which(small) else seq(along=small)[small]