pimp.import: Predictor Importance – Variables and Interactions

In LogicForest: Logic Forest

Predictor Importance – Variables and Interactions

Description

Calculates permutation-based importance measures for individual predictors and interactions within a logic regression tree in a logic forest.

Usage

pimp.import(fit, data, testdata, BSpred, pred, Xs, mtype)

Arguments

fit	Fitted logic regression tree object containing outcome, model type, and logic tree information.
data	In-bag sample (training data).
testdata	Out-of-bag sample (test data).
BSpred	Number of predictors included in the interactions (includes NOT-ed variables).
pred	Number of predictors in the model (used for constructing permuted matrices).
Xs	Matrix or data frame of 0/1 values representing all predictor variables.
mtype	Model type: "classification", "linear", "Cox-PH Time-to-Event", or "Exp. Time-to-Event".

Details

This function calculates importance measures for each bootstrapped sample by comparing model fit between the original out-of-bag sample and a permuted out-of-bag sample. Model fit is evaluated using:

• Misclassification rate for classification models,

• Log2 mean squared error for linear regression,

• Harrell's C-index for survival regression (Cox-PH or exponential time-to-event models).

Value

A list with the following components:

single.vimp

Vector of importance estimates for individual predictors.

pimp.vimp

Vector of importance estimates for interactions (pimps).

Ipimat

Matrix indicating which predictors (and NOT-ed predictors) are used in each interaction.

vec.Xvars

Vector of predictor IDs used in the tree.

Xids

Vector of predictor column indices corresponding to vec.Xvars.

Author(s)

Bethany J. Wolf [e-mail]
J. Madison Hyer [e-mail]

References

Wolf BJ, Hill EG, Slate EH. Logic Forest: an ensemble classifier for discovering logical combinations of binary markers. Bioinformatics. 2010;26(17):2183–2189. \Sexpr[results=rd]{tools:::Rd_expr_doi("10.1093/bioinformatics/btq354")}

See Also

logforest

LogicForest documentation built on Feb. 14, 2026, 1:08 a.m.