This example shows a correlation matrix for abalone physical measurements, split by sex (Male, Female, or Infant). The upper triangle uses a red-blue color scale to encode correlation strength, while the lower triangle displays the numeric correlation values. A dropdown menu filters the matrix by sex category. The visualization is built with D3 v6, using `scaleBand` for axes, `scaleSequential` with `interpolateRdBu` for colors, and computes Pearson correlations from CSV data parsed with `d3.csvParseRows`.