Using Vega-Lite I can use aggregate inside an encoding like so:

I am prototyping something with Vega-Lite index chart https://vega.github.io/vega-lite/examples/interactive_index_chart.html

I am prototyping something with Vega-Lite index chart https://vega.github.io/vega-lite/examples/interactive_index_chart.html

I am prototyping something with Vega-Lite index chart https://vega.github.io/vega-lite/examples/interactive_index_chart.html

I would like to create sub-vizualizations in Vega using the group mark. Below you will find a minimal example where the second plot is overlapping with the first one as it can be seen in the title.