shapr (version 1.0.1)

create_coalition_table: Define coalitions, and fetch additional information about each unique coalition

Description

Define coalitions, and fetch additional information about each unique coalition

Usage

create_coalition_table(
  m,
  exact = TRUE,
  n_coalitions = 200,
  weight_zero_m = 10^6,
  paired_shap_sampling = TRUE,
  prev_coal_samples = NULL,
  prev_coal_samples_n_unique = NULL,
  n_samps_scale = 10,
  coal_feature_list = as.list(seq_len(m)),
  approach0 = "gaussian",
  kernelSHAP_reweighting = "none",
  dt_valid_causal_coalitions = NULL
)

Value

A data.table with info about the coalitions to use

Arguments

m

Positive integer. Total number of features/groups.

exact

Logical. If TRUE all 2^m coalitions are generated, otherwise a subsample of the coalitions is used.

n_coalitions

Positive integer. Note that if exact = TRUE, n_coalitions is ignored.

weight_zero_m

Numeric. The value to use as a replacement for infinite coalition weights when doing numerical operations.

paired_shap_sampling

Logical. Whether to do paired sampling of coalitions.

prev_coal_samples

Character vector. A vector of previously sampled coalitions as characters. Each string contains a coalition and the feature indices in the coalition is separated by a space. For example, "1 5 8" is a coalition with features 1, 5, and 8.

prev_coal_samples_n_unique

Positive integer. The number of unique coalitions in prev_coal_samples. This is a separate argument to avoid recomputing the number unnecessarily.

n_samps_scale

Positive integer. Integer that scales the number of coalitions n_coalitions to sample as sampling is cheap, while checking for n_coalitions unique coalitions is expensive, thus we over sample the number of coalitions by a factor of n_samps_scale and determine when we have n_coalitions unique coalitions and only use the coalitions up to this point and throw away the remaining coalitions.

coal_feature_list

List. A list mapping each coalition to the features it contains.

approach0

Character vector. Contains the approach to be used for estimation of each coalition size. Same as approach in explain().

dt_valid_causal_coalitions

data.table. Only applicable for asymmetric Shapley values explanations, and is NULL for symmetric Shapley values. The data.table contains information about the coalitions that respects the causal ordering.

Author

Nikolai Sellereite, Martin Jullum, Lars Henry Berge Olsen

Examples

if (FALSE) {
# All coalitions
x <- create_coalition_table(m = 3)
nrow(x) # Equals 2^3 = 8

# Subsample of coalitions
x <- shapr:::create_coalition_table(m = 10, exact = FALSE, n_coalitions = 1e2)
}