This example visualizes the classic Iris dataset by encoding each of the 150 flowers as a sector in a donut chart. Each data row is mapped to a single pie slice with equal angular width, and each slice is filled with a randomly generated hex color. The visualization is rendered as an SVG using React, with the pie geometry computed by the `d3.pie()` encoder and slice paths generated via the `d3.arc()` function. Data is loaded asynchronously from a CSV URL using `d3.csv`.