This example demonstrates data transformation from a CSV file using D3.js. The visualization loads fruit pricing data and calculates the average sepal length for each species using `flatRollup` and `sum`. The transformed data is then rendered as a JSON string in a `<pre>` element. The code utilizes `csvParse` for data ingestion, `select` for DOM manipulation, and the `flatRollup` aggregation API to summarize the dataset.