Reference

ssb_kostra_python package

ssb_kostra_python.kommunekorr module

kostra_kommunekorr(year)

Fetches and compiles data on correspondences between municipalities and related classifications for a given year.

The function retrieves the following:

  • Municipality classification (KLASS 131) and manually adds Longyearbyen.

  • The correspondence between municipality (KLASS 131) and KOSTRA group (KLASS 112). This request is wrapped in a try-except block to catch HTTP 404 errors and raise a descriptive ValueError.

  • The correspondence between municipality (KLASS 131) and county (KLASS 104).

The retrieved data is merged into a single DataFrame containing information on:

  • Municipality number (komm_nr) and name (komm_navn)

  • County number (fylke_nr) and name (fylke_navn)

  • KOSTRA group number (kostra_gr) and name (kostra_gr_navn)

  • Validity start and end dates for both KOSTRA group and county classifications.

  • Additional columns:

    • ‘fylke_nr_eka’: county number prefixed with “EKA”.

    • ‘fylke_nr_eka_m_tekst’: concatenation of ‘fylke_nr_eka’ and the county name.

    • ‘landet’: a static label “EAK Landet”.

    • ‘landet_u_oslo’: a static label “EAKUO Landet uten Oslo” (set to NaN for Oslo, municipality code “0301”).

Parameters:

year (str) – The year (format “YYYY”) for which data should be fetched.

Returns:

A DataFrame with the following columns:

  • komm_nr: Municipality number.

  • komm_navn: Municipality name.

  • fylke_nr: County number.

  • fylke_navn: County name.

  • fylke_nr_eka: County number prefixed with “EKA”.

  • fylke_nr_eka_m_tekst: Combination of fylke_nr_eka and fylke_navn.

  • fylke_validFrom: Start date for county classification validity.

  • fylke_validTo: End date for county classification validity.

  • kostra_gr: KOSTRA group number.

  • kostra_gr_navn: KOSTRA group name.

  • kostra_validFrom: Start date for KOSTRA group validity.

  • kostra_validTo: End date for KOSTRA group validity.

  • landet: Static label for the nation.

  • landet_u_oslo: Static label for the nation excluding Oslo.

Return type:

pd.DataFrame

Raises:

ValueError – If the correspondence between municipality and KOSTRA group is not found (e.g., HTTP 404), or if duplicates are detected for municipality numbers after merging the data.

Example

>>> df = kostra_kommunekorr("2025")
>>> df['verdi'] = 1000
>>> groups = [
...     ['komm_nr', 'komm_navn'],
...     ['fylke_nr', 'fylke_navn'],
...     ['kostra_gr', 'kostra_gr_navn'],
...     ['landet_u_oslo'],
...     ['landet']
... ]
>>> agg_list = []
>>> for cols in groups:
...     temp = df.groupby(cols)['verdi'].sum().rename('agg_verdi')
...     agg_list.append(temp)
>>> df_agg = pd.DataFrame(pd.concat(agg_list))