Region Mapping (Cross-Source to 2024 Counties)

This document defines the canonical region model for cross-source maps and choropleths.

Goal

Use one shared region spine for visualization across sources:

• Canonical level: 15 Norwegian counties (2024 reform)
• Exclude: Svalbard and Jan Mayen
• Keep source-native region ids for drilldown and provenance

BRIS counties.ids for pre-2024 incidents (klass 104 codes such as Viken 30) are listed only in source-api-request-examples.md (“Norwegian Fylke Code Reference”); post-2024 request ids match canonical_code in the table below.

Canonical region set (2024, county level)

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Source-to-canonical mapping rules

1) BRASK (Cresta-sone, pre-2020 counties)

BRASK region ids are old county boundaries. Convert at query/render time to canonical 2024 counties:

Explicit exclusions:

• 21 (Svalbard): excluded from canonical choropleth
• 22 (Jan Mayen): excluded from canonical choropleth
• 99 (Ukjent): excluded from county choropleth; can be shown as "Unknown" side bucket

2) BRIS (current administrative geography)

BRIS supports county and municipality filters.

• County IDs are current administrative codes.
• Municipality IDs are finer-grain and should roll up to canonical county via municipality-to-county lookup.

Canonical handling:

• If BRIS county id is one of 03,11,15,18,31,32,33,34,39,40,42,46,50,55,56, map directly.
• If BRIS data includes historical merged county ids (for example 30, 38, 54), resolve by municipality-level attribution when possible; otherwise mark as non-canonical aggregate and exclude from strict county choropleth.

Merged county fallback mapping (only when municipality detail is unavailable):

Rule: do not allocate merged totals proportionally unless explicitly approved; keep as non-canonical aggregate.

3) SSB

Per ssb.md, region coding depends on table:

• 12058: municipality codes (4-digit), no county selector
• 06266, 03173, 03158: include county-level 2-digit region codes

Canonical handling:

• County-level SSB codes matching the 15-county list map directly.
• Municipality-level SSB codes must be rolled up to county using municipality-to-county mapping.
• 0 / national totals are not county entities and should not be painted as a county.

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Choropleth contract (recommended)

For all sources, expose these fields in map-serving queries:

• canonical_region_code (2-digit county code)
• canonical_region_name
• source_id
• source_native_region_code
• source_native_region_name
• is_canonical (boolean)

Rendering rules:

1. County choropleth uses only is_canonical = true.
2. Drilldown panel shows source-native region labels and ids.
3. Unknown/non-canonical aggregates (for example BRIS 30, BRASK 99) are listed outside the map.

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Implementation notes for filters

When seeding fire_data.filters:

• Keep source-native region rows (axis='region') as-is with stable native_code.
• Assign standard_code for every row (canonical county code, ALL, UNKNOWN, SVALBARD_JAN_MAYEN, etc.).
• Choropleth joins use standard_code; native filters.id stays on facts for provenance.