This example displays a correlation matrix for the mtcars dataset, with each cell showing the correlation coefficient between two variables, either as a numerically labeled square or a colored circle. The color scale encodes the strength and direction of correlation, ranging from red for negative through white for zero to dark blue for positive values. The visualization uses D3.js version 3 with an ordinal scale for positioning and a linear color scale, rendering as SVG. A vertical color legend with axis is included on the right side.