This example displays a scatterplot of colorful circles loaded from a CSV file, with click interaction to highlight a selected node. Written in React, it uses D3’s `selectAll` and `data` join to bind CSV rows to SVG circle elements, mapping `cx`, `cy`, `r`, and `fill` attributes. A React `useState` hook tracks the selected circle’s ID, and clicking a circle triggers a re-render that adds a black stroke to the chosen node. The code imports `csv` from D3 to parse the data and passes it to a reusable `viz` function that updates the visualization.