Calendar Heatmap
This calendar heatmap combines a yearly calendar view with a day-hour heatmap, showing monthly data across 24-hour segments with color-coded values. The visualization renders two SVG charts: a calendar grid for each month and a detailed hour-by-day matrix, both using D3 v3 with quantile color scales and d3-tip tooltips. Sample data includes daily amounts for January 2017, color-coded through custom color schemes and animated transitions for interactive exploration.