These donut charts are constructed from a CSV file storing the populations of various age groups in different states. (As a practical note, a normalized stacked area chart facilitates easier comparison of values.) The chart employs a number of D3 features:
- d3.csv - load and parse data
- d3.scale.ordinal - color encoding
- d3.keys - compute column names
- d3.svg.arc - display arcs
- d3.layout.pie - compute arc angles from data