Support for Discrete Color Mapping in Heatmap DataTrack for Copy Number Visualization

[davidcoffey]

Thank you for developing and maintaining the Gviz package, which has been instrumental in genomic data visualization for many researchers. I would like to request a new feature that I believe would enhance the package’s usability and consistency for users working with copy number variation (CNV) data. It would be incredibly helpful if the heatmap DataTrack supported discrete color mapping. This functionality would allow users to define custom color mappings for specific copy number states, ensuring consistent and interpretable visualizations of CNV data across different samples. For example:
• < 2 copies (deletion): Shades of blue
• 2 copies (neutral): White
• > 2 copies (gain): Shades of red

Currently, the package uses continuous gradients, which can make it challenging to ensure consistent visualization across datasets.