d3 scatterplot matrix
This scatterplot matrix visualizes North American population-health indicators, comparing fertility rate, life expectancy, and population growth across the United States, Canada, and Mexico. Each of the nine charts plots one variable against another, with data points colored by country using a d3.scaleOrdinal color scale and a legend rendered in SVG. The code loads data from a CSV file via d3.csv, filters incomplete records, and uses d3.scaleLinear, d3.axisBottom, d3.axisLeft, and d3.extent to build axes and scale the plots.