rv (version 1.0)

constant: Constant Vectors

Description

Tests or coerces objects that are non-random.

Usage

is.constant(x)
 as.constant(x)
 ## S3 method for class 'rv':
as.constant(x)

Arguments

x

an object, random variable (rv) or not

Details

is.constant returns TRUE for each component of the argument object if there is only one simulation (that is, the variable is ``constant").

Note: rv objects that merely have variance zero are not therefore necessarily constants.

References

Kerman, J. and Gelman, A. (2007). Manipulating and Summarizing Posterior Simulations Using Random Variable Objects. Statistics and Computing 17:3, 235-244.

See also vignette("rv").

Examples

is.constant(1)         # TRUE
  is.constant(as.rv(1))  # TRUE
  setnsims(200)
  x <- rvbern(prob=0.001)
  all(sims(x)==0)        # most probably true
  is.constant(x)         # always FALSE