Statistics Norway vessels in foreign-going trade (StatBank 07321)

curl -sS -X POST 'https://data.ssb.no/api/v0/en/table/07321' -H 'Content-Type: application/json' -d '{"query":[{"code":"ContentsCode","selection":{"filter":"item","values":["Reisecert"]}},{"code":"Tid","selection":{"filter":"top","values":["5"]}}],"response":{"format":"json-stat2"}}' 

"""SSB StatBank 07321 vessels in foreign-going trade sample query (JSON-stat2 → labeled rows)."""
import requests
import pandas as pd
from itertools import product

URL = "https://data.ssb.no/api/v0/en/table/07321"
query = {
    "query": [
        {"code": "ContentsCode", "selection": {"filter": "item", "values": ["Reisecert", "Fraktkontr", "Linjefrakt"]}},
        {"code": "Tid", "selection": {"filter": "top", "values": ["10"]}},
    ],
    "response": {"format": "json-stat2"},
}
r = requests.post(URL, json=query, timeout=60)
r.raise_for_status()
js = r.json()
vals = js.get("value") or []
dims = js.get("id") or []
size = js.get("size") or []
dimension = js.get("dimension") or {}

def labels_for(dim_id: str):
    cat = dimension[dim_id]["category"]
    index = cat["index"]
    # index maps category-id -> position
    by_pos = [None] * len(index)
    for key, pos in index.items():
        by_pos[pos] = key
    lab = cat.get("label") or {}
    return by_pos, lab

# JSON-stat stores values in row-major order with the last dimension changing fastest.
axes = [list(range(s)) for s in size]
rows = []
for coords in product(*axes):
    flat = 0
    mul = 1
    for c, s in zip(reversed(coords), reversed(size)):
        flat += c * mul
        mul *= s
    row = {"value": vals[flat]}
    for dim_id, c in zip(dims, coords):
        by_pos, lab = labels_for(dim_id)
        cid = by_pos[c]
        row[dim_id] = cid
        row[f"{dim_id}_label"] = lab.get(cid, cid)
    rows.append(row)

df = pd.DataFrame(rows)
print("HTTP", r.status_code, "rows", len(df), "label", js.get("label"))
print(df.head().to_string(index=False))
df.to_parquet("ssb_07321_sample.parquet", index=False)