This example shows a circle-packing visualization of eight data groups labeled A through H, where each circle’s area is proportional to a numeric value. Every two seconds, the visualization toggles between displaying the group’s total and its percentResponse metric. Using D3 v7’s `d3.pack` and `d3.hierarchy`, the circles animate smoothly to new positions and sizes via a `d3.transition` with a linear ease. The code renders to SVG, updating circle radii and text labels for the current value on each cycle.