Series-delta charts

A series-delta chart draws one bar per series. Each bar is the series value in its ending year minus its value in its starting year.

Compare one interval

- chartpack:
    format: gcubed-chartpack
    version: "1.2.0"
    title: Endpoint changes
- chart:
    title: Change in real GDP, 2025–2050
    chart_type: series-delta
    start_year: 2025
    end_year: 2050
    series:
      - variable_prefix: GDPR
        selectors:
          regions: [USA, ROW]

The calculation is always end_year value - start_year value. Its interpretation comes from the projections supplied to that report. Level projections produce a change in levels; deviation projections produce a change in deviations. There is no separate levels-or-deviations field in the chartpack. If an inflation deviation rises from 0.2 to 0.5 percentage points, the bar is +0.3 percentage points. The template does not calculate a percentage growth rate or subtract a second experiment file.

See the illustrated delta example for the chart and its complete YAML.

Give one series different endpoints

Pack, section and chart years provide defaults. On a series-delta chart, an exact or selector series can override either endpoint:

- chart:
    title: Changes over selected periods
    chart_type: series-delta
    start_year: 2025
    end_year: 2050
    series:
      - variable: GDPR(USA)
      - variable: GDPR(ROW)
        start_year: 2030
        end_year: 2040

Endpoint precedence is series, chart, active section, then chartpack defaults. Every series needs two effective endpoints, and its starting year must be before its ending year. The template does not infer these endpoints from the first and last CSV columns. Both endpoint observations must be finite numbers; a blank or missing endpoint omits that bar with a warning. Series-level years apply only to series-delta charts.

All bars in one chart must have the same units and variable prefix. Their projection metadata must have the same ordered dimension names, and the series may vary across no more than one dimension. These rules keep the bar comparison meaningful. An exact-series style.color controls its bar colour; style.line has no effect.

The chart’s data table and per-chart CSV export identify each series, its initial year, its final year and the calculated difference. Image exports show the same bar chart displayed on the page.

With version: "1.4.0", delta bars may also use orientation, sort, color_by_sign, show_labels, and custom axis labels. See the display recipes.

Labels, styles and units