This example visualizes the Iris dataset with a scatter plot comparing petal length on the x-axis against petal width on the y-axis, coloring each point by species (setosa, versicolor, virginica) via a switch function. The chart also encodes sepal length and width as the rx and ry attributes of each circle, creating elliptical markers. It loads CSV data using d3.csv, applies linear scales with d3.scaleLinear, and renders axes with d3.axisLeft and d3.axisBottom. The SVG output also includes rotated axis labels for clarity.