Hello everyone, I'm new here. Recently, I recreated the chart titled "The Radiant Energy Spectrum". I learned about d3.arc( ) from Patrick Wojda's excellent notebook "Radial hierarchical bar chart with grouping arcs," obtained the visible spectrum data from Mike Bostock, and wrote my own functions to arrange line segments, arrows, and brackets along the arcs. The rest was just adding labels. The colors and fonts are still pretty terrible, and I haven't implemented the icon in the center yet.