fwh_migration

A Facetwork domain that builds a world net-migration map over time — a diverging country choropleth with a year slider (1960–2025) + play:

• 🟢 green = net immigration (more people arrive than leave)
• 🔴 red = net emigration (more leave than arrive)

shaded by net migration per 1,000 population, so small countries with large relative flows show up alongside the big ones. Click any country for its net migration count + rate that year and its by-decade history.

Live: rlemke.github.io/facetwork-maps/world/net-migration

Data

• World Bank — Net migration (SM.POP.NETM) + Total population (SP.POP.TOTL), one open API call each (no key), joined onto Natural Earth country geometry by ISO3. Net migration = immigrants − emigrants (a UN World Population Prospects–derived estimate).
• Honest scope: ~65 years is the longest openly-available global migration series — consistent per-country data does not exist for the early 20th century, so "100 years" isn't possible from an authoritative open source.

Workflow

migration.workflows.BuildMigrationWorldMap
  ├─ migration.sources.DownloadMigration   # WB net-migration + population, cached
  └─ migration.maps.BuildMigrationMap      # join → per-year rate → year-slider HTML

Output → cache/migration/output/index.html (MinIO on the fleet), published to the facetwork-maps gallery via the generic PublishToSite.

Layout

src/migration/
  _lib.py            # WB fetch + ISO3 join + diverging year-slider renderer
  storage.py         # backend-aware paths (local / MinIO), shared cache
  handlers/          # thin event-facet handlers over _lib
  ffl/migration.ffl  # DownloadMigration + BuildMigrationMap + BuildMigrationWorldMap
tests/               # offline (WB API + geometry mocked)

Run

pip install -e .          # requests only
python -m pytest tests/ -q