Improve code quality: proper logging, error handling, and optional de…

[Alanperry1]

Summary

This PR improves code quality across the codebase by replacing print() statements with proper logging, converting assert statements to explicit error handling with clear error messages, and moving matplotlib from a required dependency to an optional visualization dependency.

Changes

Logging Improvements

• tools/train_net.py: Moved command line args logging to after default_setup() is called, ensuring proper logging configuration
• tools/visualize_data.py: Replaced print() calls with logger.info() for file output messages
• datasets/prepare_panoptic_fpn.py:
  • Added logging import at the top of the file (proper Python convention)
  • Replaced print() statements with logger.info() for progress messages

Error Handling

• demo/demo.py: Converted all assert statements to explicit ValueError/FileNotFoundError exceptions with descriptive error messages:
  • Input path validation
  • Output path validation
  • Webcam/input conflict validation
  • Video file existence checks
  • Removed redundant assert os.path.isdir(args.output) check that was logically impossible

Dependency Management

• setup.py: Moved matplotlib from install_requires to extras_require["viz"], completing the TODO
• detectron2/utils/visualizer.py: Added try-except block around matplotlib imports with helpful error message directing users to install detectron2[viz]

Benefits

• Better logging control and consistency across the codebase
• More informative error messages for debugging
• Reduced required dependencies - matplotlib only needed for visualization features
• Users can now install with pip install detectron2 for core functionality or pip install detectron2[viz] for visualization features

Breaking Changes

Users who don't install the viz extra will need to run pip install detectron2[viz] to use visualization features.

[Copilot]

Pull request overview

This PR improves code quality by replacing print() statements with proper logging, converting assert statements to explicit error handling with descriptive error messages, and moving matplotlib from a required dependency to an optional visualization dependency.

Changes:

• Replaced print() calls with logger.info() in visualization and training tools
• Converted assert statements to explicit exceptions (ValueError, FileNotFoundError) with clear error messages in demo.py
• Moved matplotlib to extras_require["viz"] in setup.py and added import handling in visualizer.py

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
tools/visualize_data.py	Replaced print statements with logger.info for file output messages
tools/train_net.py	Moved command line args logging to after default_setup() for proper configuration
setup.py	Moved matplotlib from install_requires to extras_require["viz"]
detectron2/utils/visualizer.py	Added try-except for matplotlib imports with helpful error message
demo/demo.py	Converted assert statements to explicit exceptions with descriptive messages
datasets/prepare_panoptic_fpn.py	Added logging import and replaced print statements with logger.info

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[Copilot]

The video file existence check is performed after the output file setup (lines 164-180). This means if the video input file doesn't exist, the code will still create the output file writer first, potentially creating an empty output file before failing. The video file existence check should be moved earlier, before any output file setup, to fail fast and avoid creating unnecessary files.

[Alanperry1]

@copilot open a new pull request to apply changes based on this feedback