A four-by-four scatter plot matrix compares every pair of numeric measurements in the iris dataset, with points colored by species using the `d3.scaleOrdinal` schemeSet1 palette. Each cell renders an SVG with `d3.axisLeft` and `d3.axisBottom` scales, while diagonal panels label their corresponding feature. The code fetches the CSV via `d3.csv`, parses numeric fields, and loops through all combinations to append individual SVGs sized to a quarter of the window. D3 v6 is loaded from a CDN and used as a browser global.