add-iso3166

Add ISO 3166 Country Codes

Add ISO 3166-1 codes to a dataset whose country column contains plain names.

When to invoke

• Dataset has a country column (named country, nation, country_name, or similar) but no ISO code column.
• User asks to "add country codes", "add ISO codes", "enrich with ISO 3166".

Procedure

1. Locate the dataset — confirm file path and format (CSV, JSON, JSONL, Parquet, XLSX).
2. Identify the country column — if multiple candidates exist or the column is ambiguous, ask the user which column holds the country name.
3. Check for pre-existing codes — if an ISO column already exists, report and ask whether to overwrite or skip.
4. Load data with pandas (pd.read_csv, pd.read_json, pd.read_parquet, pd.read_excel).
5. Resolve country names to ISO codes using pycountry:
   • Try exact match first via pycountry.countries.get(name=...) and .lookup(...).
   • For fuzzy/partial matches, use pycountry.countries.search_fuzzy(...) with a confidence threshold.
   • Common aliases to hard-code before fuzzy matching: USA/U.S./U.S.A. → United States, UK → United Kingdom, Russia → Russian Federation, South Korea → Korea, Republic of, North Korea → Korea, Democratic People's Republic of, Ivory Coast → Côte d'Ivoire, Czech Republic → Czechia, Burma → Myanmar.
6. Add columns: iso3166_alpha2, iso3166_alpha3, iso3166_numeric. Ask the user if they want all three or a subset — default to all three.
7. Report unresolved rows — list every country value that could not be mapped, with row counts. Do not silently drop or leave blank without reporting.
8. Write output — save alongside the input with _iso3166 suffix by default (e.g. countries.csv → countries_iso3166.csv), preserving the input format. Confirm path with user if ambiguous.
9. Update the data dictionary — if a data dictionary exists in the same folder (see add-data-dictionary / update-data-dictionary skills), add the new columns. If none exists, offer to create one.

Dependencies

pip install pandas pycountry openpyxl pyarrow

Edge cases

• Subnational regions (e.g. "Scotland", "Catalonia") — flag and ask user whether to map to parent country or leave blank.
• Historical entities ("USSR", "Yugoslavia", "Czechoslovakia") — ISO 3166-3 covers these; offer that as an option.
• Multi-country rows (e.g. "Germany / France") — flag and ask user how to handle (split, skip, keep first).
• Empty / null country values — leave ISO columns null; report count.