Add global option to skip households on simulation failure

[i-am-sijia]

This PR addresses issue #892.

Status: Draft - core functionality implemented, remaining: logging and documentation.

Summary

Adds a new skip_failed_choices setting that allows ActivitySim to skip households that cause choice model failures instead of being masked and forced a choice by the overflow_pretection or crashing the entire simulation. This improves robustness for large-scale production runs where occasional edge cases shouldn't halt the model.

Key Changes

Core Logic (activitysim/core/)

• Modified logit.py to temporarily mark failed choices with -99 and track skipped households in state
• Added functionality in state.py to dynamically drop data that belong to the skipped household
• Updated simulate.py and interaction_sample_simulate.py to handle failed choices
• Enhanced report_bad_choices() to log skipped households

Configuration

• Added skip_failed_choices: bool = True setting in top.py

Model Updates (activitysim/abm/models/)

• Retained household_id in chooser columns across location choice models for tracking
• Modified shadow price calculations to exclude skipped households
• Updated trip matrices to adjust household expansion weights: weight * (valid_hh / total_hh)
• Added null trip mode handling in trip mode choice and school escorting

Testing

• Added new unit test test/skip_failed_choices to deliberately trigger failures and validates households being skipped

Usage

# settings.yaml
skip_failed_choices: true

Access skipped household info via:

• state.get("num_skipped_households", 0)
• state.get("skipped_household_ids", set())

Final count logged at end of simulation in the activitysim.log.

Notes

• Defaults to True for production robustness
• Disables overflow protection when active to surface underlying issues
• Temporary code adds household_id to chooser columns (remove when PR Access to global constants and removing chooser col filtering #1017 merges)

[i-am-sijia]

For components where we intentionally allow some choices to fail without being skipped, the allow_zero_probs option is already set to True, which exempts them from this new feature. Therefore, it may not be necessary to introduce this as a component-level setting. In addition, keeping it as a global setting helps reduce manual errors, avoid confusion, and prevent inconsistencies across the implementation.