ccharts

https://github.com/dethrandir/ccharts

A Ruby binding to the ccharts single-header C library. Turns OHLC / sample data into text charts (line, candle, pie/donut, histogram, sparkline, bar, stacked bar, heatmap, box plot). The vendored C ABI is compiled from source by mkmf and driven through Fiddle, so there are no runtime dependencies beyond the Ruby standard library.