This example visualizes daily solar energy production data from a Bloomington Parks & Recreation site by encoding wattage values through bar length. The visualization arranges seven rectangles along an x-axis, where each bar’s height corresponds to the wattage measurement for a given day. The implementation uses D3 v7 with a band scale for positioning the bars and renders them as SVG rectangles. Color is applied via the `schemeCategory10` palette, and the code structure separates the bar-drawing logic into a reusable `length` function that receives the dataset and height parameters.