registry_for_criterion_methods function

Registry for Criterion Methods

A registry to manage methods used by criterion() to calculate a criterion value given data and a permutation. data

Format

An object of class criterion_registry (inherits from registry) of length 21.

registry_criterion

list_criterion_methods(kind, names_only = TRUE)

get_criterion_method(kind, name)

set_criterion_method(
  kind,
  name,
  fun,
  description = NULL,
  merit = NA,
  control = list(),
  verbose = FALSE,
  ...
)

## S3 method for class 'criterion_method'
print(x, ...)

Arguments

• kind: the data type the method works on. For example, "dist", "matrix" or "array".
• names_only: logical; return only the method name. FALSE returns also the method descriptions.
• name: the name for the method used to refer to the method in the function criterion().
• fun: a function containing the method's code.
• description: a description of the method. For example, a long name.
• merit: logical; indicating if the criterion measure is a merit (TRUE) or a loss (FALSE) measure.
• control: a list with control arguments and default values.
• verbose: logical; print a message when a new method is registered.
• ...: further information that is stored for the method in the registry.
• x: an object of class "criterion_method" to be printed.

Returns

• list_criterion_method() results is a vector of character strings with the names of the methods used for criterion().
• get_criterion_method() returns a given method in form of an object of class "criterion_method".

Details

All methods below are convenience methods for the registry named registry_criterion.

list_criterion_method() lists all available methods for a given data type (kind). The result is a vector of character strings with the short names of the methods. If kind is missing, then a list of methods is returned.

get_criterion_method() returns information (including the implementing function) about a given method in form of an object of class "criterion_method".

With set_criterion_method() new criterion methods can be added by the user. The implementing function (fun) needs to have the formal arguments x, order, ..., where x is the data object, order is an object of class ser_permutation_vector and ... can contain additional information for the method passed on from criterion(). The implementation has to return the criterion value as a scalar.

Examples

## the registry
registry_criterion

# List all criterion calculation methods by type
list_criterion_methods()

# List methods for matrix
list_criterion_methods("matrix")

# get more description
list_criterion_methods("matrix", names_only = FALSE)

# get a specific method
get_criterion_method(kind = "dist", name = "AR_d")

# Define a new method (sum of the diagonal elements)

## 1. implement a function to calculate the measure
criterion_method_matrix_foo <- function(x, order, ...) {
if(!is.null(order)) x <- permute(x,order)
    sum(diag(x))
}

## 2. Register new method
set_criterion_method("matrix", "DiagSum", criterion_method_matrix_foo,
    description = "Calculated the sum of all diagonal entries", merit = FALSE)

list_criterion_methods("matrix")
get_criterion_method("matrix", "DiagSum")

## 3. use all criterion methods (including the new one)
criterion(matrix(1:9, ncol = 3))

See Also

This registry uses registry::registry .

Other criterion: criterion()

Author(s)

Michael Hahsler