Dummy algorithm routine to test the sampling procedures

This is a dummy algorithm routine to test the sampling procedures, in combination with dummyinstance(). dummyalgo() receives two parameters that determine the distribution of performances it will exhibit on a hypothetical problem class: distribution.fun (with the name of a random number generation function, e.g. rnorm, runif, rexp etc.); and distribution.pars, a named list of parameters to be passed on to distribution.fun. The third parameter is an instance object (see calc_nreps() for details), which is a named list with the following fields:

• FUN = "dummyinstance" - must always be "dummyinstance" (will be ignored otherwise).

• distr - the name of a random number generation function.

• ... - other named fields with parameters to be passed down to the function in distr.

dummyalgo(
  distribution.fun = "rnorm",
  distribution.pars = list(mean = 0, sd = 1),
  instance = list(FUN = "dummyinstance", distr = "rnorm", mean = 0, sd = 1)
)

Arguments

distribution.fun

name of a function that generates random values according to a given distribution, e.g., "rnorm", "runif", "rexp" etc.

distribution.pars

list of named parameters required by the function in distribution.fun. Parameter n (number of points to generate) is unnecessary (this routine always forces n = 1).

instance

instance parameters (see Details).

Value

a list object with a single field $value, containing a scalar numerical value distributed as described at the end of Details.

Details

distribution.fun and distribution.pars regulate the mean performance of the dummy algorithm on a given (hypothetical) problem class, and the between-instances variance of performance. The instance specification in instance regulates the within-instance variability of results. Ideally the distribution parameters passed to the instance should result in a within-instance distribution of values with zero mean, so that the mean of the values returned by dummyalgo is regulated only by distribution.fun and distribution.pars.

The value returned by dummyalgo is sampled as follows:

   offset <- do.call(distribution.fun, args = distribution.pars)
   y <- offset + do.call("dummyinstance", args = instance)

See also

dummyinstance()

Author

Felipe Campelo (fcampelo@ufmg.br, f.campelo@aston.ac.uk)

Examples

# Make a dummy instance with a centered (zero-mean) exponential distribution:
instance = list(FUN = "dummyinstance", distr = "rexp", rate = 5, bias = -1/5)

# Simulate a dummy algorithm that has a uniform distribution of expected
# performance values, between -25 and 50.
dummyalgo(distribution.fun = "runif",
          distribution.pars = list(min = -25, max = 50),
          instance = instance)
#> $value
#> [1] -7.523163
#>