Chart Editing

Edit .chart.yml files that define OWID Grapher chart configurations, then preview changes.

File Locations

Chart configs: etl/steps/graph/<namespace>/<version>/<short_name>.chart.yml
Schema: schemas/chart-schema.json (read this to understand valid fields)
DAG definitions: dag/graph/<namespace>.yml (maps graph steps to data dependencies)

Before Editing

Read the schema at schemas/chart-schema.json to understand all valid fields, enums, and nested structures
Read the target .chart.yml to understand current config
Check the DAG in dag/graph/<namespace>.yml to understand which dataset the chart depends on

Chart Config Formats

Simple format (single indicator)

Used for charts with one indicator and no dimension toggles:

title: Which countries have banned chick culling?
tab: map
hasMapTab: true
chartTypes: []
yAxis:
  min: auto
map:
  hideTimeline: true
  colorScale:
    customCategoryColors:
      Banned: '#4881c6'
      No laws: '#b6a28c'
    customNumericColorsActive: true
$schema: https://files.ourworldindata.org/schemas/grapher-schema.010.json
originUrl: /animal-welfare
dimensions:
  - property: y
    catalogPath: status

Key fields: dimensions[].property (y/x/size/color) and dimensions[].catalogPath (column name in the dataset).

Multi-dimensional format (explorer-like)

Used for charts with multiple indicator combinations selectable via dropdowns:

slug: covid/covid#covid_cases

definitions:
  common_views:
    - config:
        tab: map
        originUrl: ourworldindata.org/coronavirus

title:
  title: COVID-19 confirmed cases
  title_variant: ""

default_selection:
  - World
  - Europe
  - Asia

topic_tags:
  - COVID-19

dimensions:
  - slug: period
    name: Period
    choices:
      - slug: weekly
        name: Weekly
      - slug: biweekly
        name: Biweekly

  - slug: metric
    name: Indicator
    choices:
      - slug: absolute
        name: Absolute number
      - slug: per_capita
        name: Per million people

views:
  - dimensions:
      period: weekly
      metric: absolute
    indicators:
      y:
        - catalogPath: weekly_cases

  - dimensions:
      period: weekly
      metric: per_capita
    indicators:
      y:
        - catalogPath: weekly_cases_per_million

Key differences from simple: title is an object {title, title_variant}, dimensions defines UI facets (not indicators), actual indicators are in views[].indicators.y[].catalogPath.

Previewing Charts

Charts are previewed via the staging server. The staging URL follows this pattern:

http://staging-site-{branch}/grapher/{slug}

where {branch} is the current git branch name (with /._ replaced by -, truncated to 28 chars).

PNG screenshot (for visual inspection)

Fetch the PNG directly from the staging server using WebFetch:

http://staging-site-{branch}/grapher/{slug}.png?nocache

Add &tab=map or &tab=chart to control which tab is shown.

Prerequisite: The chart must be pushed to staging first. If the user has the VSCode chart preview extension open, this happens automatically via etlr --watch. Otherwise push manually:

.venv/bin/etlr graph://<namespace>/<version>/<slug> --graph --graph-push --private

Editing Workflow

Read the chart file and schema
Make edits using the Edit tool (preserve YAML comments with ruamel if needed)
Push to staging: .venv/bin/etlr graph://<namespace>/<version>/<slug> --graph --graph-push --private
Fetch the PNG from http://staging-site-{branch}/grapher/{slug}.png?nocache to verify visually
If the chart looks wrong, read the schema for correct field names/values

Common Edits

Change default tab: Set tab to chart, map, table, line, slope, discrete-bar, or marimekko
Change selected entities: Edit selectedEntityNames array
Change colors: Edit map.colorScale.customCategoryColors or colorScale.customCategoryColors
Change color scheme: Set baseColorScheme or map.colorScale.baseColorScheme (see schema for valid values)
Hide/show map tab: Set hasMapTab: true/false
Add chart note: Set note field
Change axis: Edit yAxis or xAxis with min, max, scaleType, label

Validation

Chart configs should conform to schemas/chart-schema.json. Key constraints:

tab enum: chart, map, table, line, slope, discrete-bar, marimekko
chartTypes enum items: LineChart, ScatterPlot, StackedArea, DiscreteBar, StackedDiscreteBar, SlopeChart, StackedBar, Marimekko
dimensions[].property enum: y, x, size, color, table
addCountryMode enum: add-country, change-country, disabled

chart-editing