I’m exploring the possibility of implementing a DimpVis-like interaction technique in Vega-Lite. This is inspired by an open issue in the Altair repository and the Vega Global Development example.

The DimpVis interaction technique allows for exploration of the time dimension through direct manipulation of data points. It involves:

1. Visual hint paths showing how a data item changes over time
2. Direct manipulation of data items along their hint paths to navigate through time
3. Updating all other items to reflect the new time state
4. Application to various chart types (scatter plots, bar charts, pie charts, heatmaps)

Here’s a description of the technique:

We introduce a new direct manipulation technique for interacting with visual items in information visualizations to enable exploration of the time dimension. This interaction is guided by visual hint paths which indicate how a selected data item changes through the time dimension of a visualization. Using DimpVis, navigation through time is controlled by manipulating any data item along its hint path. All other items are updated to reflect the new time. We illustrate how DimpVis can be applied to time-varying scatter plots, bar charts, pie charts and heatmaps.

My questions are:

1. Is it possible to implement the core DimpVis interaction (dragging a point along its time path) in Vega-Lite?
2. If a full implementation isn’t possible, what aspects of this interaction could be achieved in Vega-Lite?
3. Are there any existing examples or techniques in Vega-Lite that could be adapted to achieve a similar effect?
4. What would be the key challenges or limitations in implementing this in Vega-Lite compared to the full Vega implementation?

Any insights, suggestions, or examples would be greatly appreciated. This could potentially lead to an implementation in Altair as well.