Add Choropleth Maps and Geographic Data Visualization

[cliftonc]

Summary

Provide map-based visualizations for geographic data analysis, including choropleth maps (color-coded regions) and geo-scatter plots for location-based metrics.

Current State

No geographic visualization support. Users cannot visualize data on maps despite having location dimensions.

Proposed Features

Choropleth Maps

<ChoroplethChart
  dimension="Sales.country" // or state, postalCode
  measure="Sales.totalRevenue"
  mapType="world" // or 'us-states', 'europe', custom GeoJSON
  colorScale="sequential" // or 'diverging'
/>

Features:

• Color-coded regions based on measure values
• Built-in map data: World countries, US states, EU countries
• Custom GeoJSON/TopoJSON support
• Click-to-filter integration
• Hover tooltips with values

Geo-Scatter Plot

<GeoScatterChart
  latDimension="Stores.latitude"
  lngDimension="Stores.longitude"
  sizeMeasure="Stores.salesVolume"
  colorMeasure="Stores.profitMargin"
/>

Features:

• Plot points on map with lat/lng
• Size encoding for one measure
• Color encoding for another measure
• Clustering for dense areas

Geo Heat Map

• Density visualization for location data
• Continuous color gradient
• Adjustable radius and intensity

Competitor Reference

• Kepler.gl: "Large-scale WebGL-powered Geospatial Data Visualization Tool"
• Domo: "Map chart displays information using a geographic map as the backdrop"
• Google Looker Studio: "Support for BigQuery GEOGRAPHY polygons in choropleth maps"
• Zoho Analytics: "Geo Data Visualization (Map Charts)"

Technical Approach

1. Integrate Deck.gl or Mapbox GL for WebGL rendering
2. Create ChoroplethChart and GeoScatterChart components
3. Add geographic dimension type with lat/lng or region code support
4. Bundle common boundary datasets (world, US, EU) or load on demand
5. Add MapLayer configuration for styling and interactions

Dependencies

• deck.gl or mapbox-gl for rendering
• d3-geo for projections
• topojson-client for boundary data

Labels

enhancement feature-request client visualization

[last-light]

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[last-light]

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[cliftonc]

@last-light can you build this please.

[last-light]

PR opened: #627

Implements ChoroplethChart — a new built-in chart type that colour-codes geographic regions by a measure value.

Design choices:

• @nivo/geo for rendering (optional peer dep, consistent with @nivo/heatmap)
• No bundled geographic data — users supply GeoJSON via an inline JSON string (displayConfig.geoFeatures) or a URL (displayConfig.geoFeaturesUrl). This avoids adding 60–200 KB of boundary data to the bundle.
• Drop zones: region code dimension (xAxis) + measure (valueField)
• Projection selector, unknown-region colour, feature-ID property override, graticule and legend toggles
• Drill-down support via onDataPointClick

Not in this PR (can follow as separate issues): GeoScatterChart, GeoHeatMap, bundled world/US-states boundary data.