This example displays the Iris dataset as an animated scatter plot that cycles through different x-axis variables every three seconds. The plot maps petal width to the y-axis while alternating between sepal width, petal length, and sepal length on the x-axis. Species are encoded using distinct SVG symbols—stars, crosses, and diamonds—generated with d3.symbol. The reusable chart function leverages d3.scaleLinear, axisLeft, and axisBottom for scales and axes, with setInterval driving the periodic updates.