isR 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 previous to S-PLUS 8.0, 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 <- stats::runif(20); small <- x < 0.4
## In the early years of R, 'which()' only existed in R:
if(is.R()) which(small) else seq(along = small)[small]