This is a demo tutorial. While there is no step-by-step commentary available (yet), the live demo below is fully functional. Feel free to open it for full source code.
Below are two demos that use adapters to modify radii of the ColumnSeries
columns based on their value.
Vertical columns
See the Pen amCharts 4: Using adapters to tailor corner radii for positive and negative value columns by amCharts team (@amcharts) on CodePen.
Horizontal bars
See the Pen amCharts 4: Using adapters to apply corner radii based on value by amCharts team (@amcharts) on CodePen.