This example shows a scatter plot matrix for the Iris dataset, displaying pairwise relationships between sepal and petal measurements. Each off-diagonal cell contains a scatter plot colored by species, while the diagonal cells show histograms of individual traits. The visualization uses D3 v5 with SVG rendering, leveraging `d3.scaleLinear`, `d3.axisBottom`, `d3.axisLeft`, `d3.brush`, and `d3.histogram` to build the matrix. Data loads from a CSV file, and users can brush cells to explore correlations across dimensions.