This interactive punchcard chart visualizes barley yield data across multiple sites and years, with each circle’s size mapped to the yield value. A dropdown menu filters the dataset by site, and when a new site is selected, the chart transitions smoothly. The visualization uses D3 v5’s `dispatch` event system, `d3.nest()`, and `d3.map()`, along with `d3.scaleSqrt()` for circle scaling and `transition().duration(750)` for animated updates. The data is loaded from a CSV file, and the chart is rendered as SVG with ordinal axes.