How to Create a Range Spline Area Chart

What is a Range Spline Area Chart

Single-series Range Spline Area Charts render a filled-in zone between two curve (spline) lines. They require a start value and an end value for each point. In our charts, the end value will still be given by an Area chart selection. While start values require another data column to be set as Area Start.

We will have the following possible combinations:

1. Area Start + Area – standard single-series Range Spline Area chart.
2. Area Start + Area + Area Start + Area … – multi-series Grouped Spline Range Areas.
3. Area Start + Area Start + … + Area – multi-series Stacked Spline Range Areas.
4. Area Start alone – this will render a Spline chart, equivalent to a curve Line chart setting.

Multi-series Range Spline Area Charts render either one-behind-the-other Grouped Spline Areas, or Stacked Spline Areas piled one on top of the other. Portions of some areas may appear hidden for Grouped Spline Areas, so using a semi-transparent fill is recommended. Stacked Spline Areas may also overlap, when one area from the top gets negative values and goes down over the area it stays on top of.

Multiple-series Range Spline Areas are usually multi-color, each series getting a different palette color. Single-series Range Spline Areas could be single or multi-color, with each point segment getting a different palette color.

Steps to Create a Range Spline Area Chart

Start Visual Xtractor or Data Xtractor. Connect to a database. Create or design a SQL query. Run the query and check the results.

1. Display and enable the Chart query builder.
2. Set a data column as Area Charts – Area Start chart, for a simple Line chart.
3. Set another similar column as Area, for custom end values and a full Range Area chart.
4. Add other pairs of Area Start + Area, for a Grouped Range Area chart.
5. Or end a chain of Area Start with an Area, for a Stacked Range Area chart.
6. Display all areas with interpolated Curve (Spline) Lines.
7. Add an optional Label.

Single-Series Range Spline Area Chart

Set two numeric or datetime data columns to Area Start (for start values) and Area (for low values), and select a curve (spline) line for the series. In 3D, you may get a warning or an error if any start value is lower than any end value. On multi-color charts, each point is seen as a segment and colored differently.

See the 3D MultiColor Range Spline demo query.

Grouped Range Spline Area Chart

Add more than one Area Start + Area pair to a single-series Range Spline Area chart. Display all series areas with curve (spline) lines. In multi-color charts, each series gets a different color. While areas will usually overlap, use a semi-transparent fill for a better view.

See the Grouped Range Areas demo query, that you may easily adjust to show curve lines instead.

Stacked Range Spline Area Chart

Chain two or more Area Start settings, ending in an Area chart, and you basically add each area on top of each other. Display all areas with curve lines. Areas stacked this way may also overlap, on negative values. In 3D, all start values must be greater than the end values.

See the Stacked Spline Range Areas demo query.

Customize your Range Spline Area Chart

1. Show all X axis labels as data labels in block plots.
2. Hide any axes and any other text labels.
3. Switch to a 3D view, with solid fill colors.
4. You may also show straight default lines instead, in all or some series.

Conclusion

• Creating Range Spline Area charts in Data Xtractor or Visual Xtractor is fast and intuitive: for any single series, use pairs of Area Start and Area, and display Curve Lines for all areas.
• Use more than one pair for overlapping Grouped Range Spline Area charts.
• Chain several Area Start together, for a Stacked Range Spline Area chart.