Skip to content

Upgrade TreeSHAP algorithm#12179

Merged
RAMitchell merged 6 commits into
dmlc:masterfrom
RAMitchell:cpu-qshap-extract
Apr 27, 2026
Merged

Upgrade TreeSHAP algorithm#12179
RAMitchell merged 6 commits into
dmlc:masterfrom
RAMitchell:cpu-qshap-extract

Conversation

@RAMitchell
Copy link
Copy Markdown
Member

Extracted from #12106

Faster on all benchmarks and considerably more accurate for deep trees. GCC compiles to vector instructions.

Copy link
Copy Markdown
Contributor

Copilot AI left a comment

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Pull request overview

This PR upgrades the CPU exact TreeSHAP implementation by replacing the prior path-based TreeSHAP code with an 8-point quadrature-based TreeSHAP traversal, aiming to improve speed and numerical accuracy on deep trees.

Changes:

  • Removed the legacy src/predictor/treeshap.{h,cc} implementation.
  • Implemented CPU exact SHAP values and interaction values using a fixed 8-point quadrature recurrence in src/predictor/interpretability/shap.cc.
  • Added a new quadrature-rule generator utility in src/predictor/interpretability/quadrature.h and updated tests to include needed tree-view headers.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file
File Description
tests/cpp/predictor/test_shap.cc Adds an include needed for the updated SHAP implementation/types.
src/predictor/treeshap.h Deletes the legacy TreeSHAP API declarations.
src/predictor/treeshap.cc Deletes the legacy TreeSHAP implementation.
src/predictor/interpretability/shap.cc Replaces CPU exact SHAP + interaction SHAP with quadrature-based traversal and shared infrastructure.
src/predictor/interpretability/quadrature.h Introduces endpoint quadrature rule construction used by the new CPU implementation.

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

Comment thread src/predictor/interpretability/quadrature.h Outdated
Comment thread src/predictor/interpretability/shap.cc
@RAMitchell RAMitchell requested a review from trivialfis April 22, 2026 10:36
@RAMitchell RAMitchell merged commit 9fc3d4a into dmlc:master Apr 27, 2026
80 checks passed
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Labels

None yet

Projects

None yet

Development

Successfully merging this pull request may close these issues.

2 participants