buildConstraints {UBayFS}

Build a constraint system

Description

Build an inequation system from constraints provided by the user.

Usage

buildConstraints(
  constraint_types,
  constraint_vars,
  num_elements,
  rho = 1,
  block_list = NULL,
  block_matrix = NULL
)

Arguments

constraint_types

a vector of strings denoting the type of constraint to be added; options: 'max_size', 'must_link', 'cannot_link'

constraint_vars

a list of parameters defining the constraints; in case of max-size constraints, the list element must contain an integer denoting the maximum size of the feature set, in case of max-link or cannot link, the list element must be a vector of feature indices to be linked

num_elements

the total number of features (feature-wise constraints) or blocks (block-wise constraints) in the dataset

rho

a positive parameter denoting the level of relaxation; 'Inf' denotes a hard constraint, i.e. no relaxation

block_list

the list of feature indices for each block; only required, if block-wise constraints are built and 'block_matrix' is 'NULL'

block_matrix

the matrix containing affiliations of features to each block; only required, if block-wise constraints are built and 'block_list' is 'NULL'

Details

The function transforms user information about relations between features (must-link or cannot-link constraints) and maximum feature set size (max-size) into a linear inequation system. In addition, the relaxation parameter 'rho' can be specified to achieve soft constraints.

Value

a 'UBayconstraint' containing a matrix 'A' and a vector 'b' representing the inequality system 'Ax<=b', and a vector 'rho' representing the penalty shape

Examples

# given a dataset with 10 features, we create a max-size constraint limiting
# the set to 5 features and a cannot-link constraint between features 1 and 2
buildConstraints(constraint_types = c('max_size','cannot_link'),
                 constraint_vars = list(5, c(1,2)),
                 num_elements = 10,
                 rho = 1)