observablehq / observablehq/plot
Cluster contours / segmentation
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Description
For a map / scatterplot where the value is categorical, it would be nice to derive contours for each category. A way to do this might be to:
- apply a spatial interpolator to obtain a grid
- for each category c, contour the function
value === cwith a threshold of 0.5 (or 0.7 to tighten it a bit) - done
(Also applies to quantitative data, by determining categorical bands.)
There are possibly better segmentation algorithms to consider.
This is currently possible to do (but very inefficiently) by running one contour mark for each category, with a value = 1 for points that belong to the category, and -1 for points that don't.
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
No files or tests are named. Start with the existing contour mark and compare its one-mark-per-category workflow with the proposed spatial interpolation, thresholding, and segmentation approaches. Done should produce contours for categorical values and support the suggested quantitative bands, with the chosen algorithm and API clearly defined.
Written by the indexing model from the issue text.
Assessment
- Domain
- data-visualization
- Issue type
- Feature
- Difficulty
- 5/5
- Estimated time
- Over a week
- Activity status
- Stale
- Clarity
- Needs clarification
- Newbie friendliness
- 25/100