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# API Documentation
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This document describes the PX-Web API used by hagfish to fetch Faroese fisheries statistics from the official Statbank.
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## EndpointBase URL: https://statbank.hagstova.fo/api/v1/fo/H2/VV/VV01/fisknv_md.px
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- **GET**: Returns metadata (table structure, dimension codes, labels)
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- **POST**: Returns data in JSON-stat2 format
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## Metadata Request (GET)
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### Requestbash
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curl -s "https://statbank.hagstova.fo/api/v1/fo/H2/VV/VV01/fisknv_md.px"
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### Response Structurejson
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{
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"title": "AVR01010 Avreiðingar í nøgd og virði...",
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"variables": [
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{
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"code": "measure",
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"text": "mát",
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"role": null,
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"values": ["MASS", "VALUE"],
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"valueTexts": ["Nøgd", "Virði"]
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}
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]
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}
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### Fields
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| Field | Type | Description |
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|-------|------|-------------|
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| `title` | string | Table name in Faroese |
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| `variables[].code` | string | Dimension identifier (used in queries) |
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| `variables[].text` | string | Human-readable label in Faroese |
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| `variables[].role` | null/string | Classification (always `null` on this endpoint) |
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| `variables[].values` | string[] | Valid dimension codes |
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| `variables[].valueTexts` | string[] | Display labels (parallel with `values`) |
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### Verified Dimension Codes
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| Variable Code | Faroese Label | Values |
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|---------------|---------------|--------|
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| `measure` | mát | `MASS`, `VALUE` |
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| `Species (ASFIS2022)` | Fiskaslag (ASFIS2022) | `TOTAL`, `148XXXXXXX00000`, ... (72 total) |
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| `Fishing Gear (ISSCFG2016)` | Reiðskapur (ISSCFG2016) | `TOTAL`, ... (12 total) |
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| `Economic Zone (GEONOM2023)` | Búskapar øki (GEONOM2023) | `TOTAL`, ... (10 total) |
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| `Processing (EUMOFAPresentation)` | Virking (EUMOFAPresentation) | `TOTAL`, ... (6 total) |
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| `Preservation (EUMOFAPreservation)` | Viðgerð (EUMOFAPreservation) | `TOTAL`, ... (9 total) |
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| `Shipsize` | Skipastødd | `TOTAL`, ... (11 total) |
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| `month` | mánaður | `2015M01` through `2026M05` (137 months) |
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**Note**: `role` is always `null`. Time dimension identification must use `code == "month"`.
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---
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## Data Request (POST)
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### Request Body Formatjson
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{
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"query": [
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{
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"code": "dimension_code",
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"selection": {
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"filter": "item",
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"values": ["value1", "value2"]
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}
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}
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],
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"response": {
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"format": "json-stat2"
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}
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}
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### Filter Types
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| Filter | Values | Description |
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|--------|--------|-------------|
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| `item` | explicit codes | Select specific values |
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| `all` | `["*"]` | Wildcard — select all values |
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| `top` | `["TOP_N"]` | Top N values by magnitude |
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### Example Querybash
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curl -s -X POST
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-H "Content-Type: application/json"
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-d '{
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"query": [
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{"code": "month", "selection": {"filter": "item", "values": ["2024M01", "2024M02"]}},
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{"code": "Species (ASFIS2022)", "selection": {"filter": "all", "values": [""]}},
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{"code": "Fishing Gear (ISSCFG2016)", "selection": {"filter": "all", "values": [""]}},
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{"code": "Economic Zone (GEONOM2023)", "selection": {"filter": "all", "values": ["*"]}},
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{"code": "Processing (EUMOFAPresentation)", "selection": {"filter": "item", "values": ["TOTAL"]}},
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{"code": "Preservation (EUMOFAPreservation)", "selection": {"filter": "item", "values": ["TOTAL"]}},
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{"code": "Shipsize", "selection": {"filter": "item", "values": ["TOTAL"]}},
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{"code": "measure", "selection": {"filter": "item", "values": ["MASS", "VALUE"]}}
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],
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"response": {"format": "json-stat2"}
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}'
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"https://statbank.hagstova.fo/api/v1/fo/H2/VV/VV01/fisknv_md.px"
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### Cell Limit
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- Maximum cells per query: ~8,000,000
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- Recommended maximum: 1,000,000 for reliability
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- To fetch full dataset, paginate by month or use smaller dimension selections
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---
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## Response Format (JSON-stat2)
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### Structurejson
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{
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"class": "dataset",
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"label": "...",
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"id": ["measure", "Species (ASFIS2022)", ..., "month"],
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"size": [2, 72, 12, 10, 1, 1, 1, 2],
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"dimension": {
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"measure": {
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"label": "mát",
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"category": {
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"index": {"MASS": 0, "VALUE": 1},
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"label": {"MASS": "Nøgd", "VALUE": "Virði"}
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}
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}
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},
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"value": [73653738, 1234567, ...]
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}
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### Fields
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| Field | Description |
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|-------|-------------|
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| `id` | Array of dimension codes in order (defines cube layout) |
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| `size` | Cardinality per dimension (parallel with `id`) |
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| `dimension.<code>.category.index` | Maps value code → numeric position in dimension |
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| `dimension.<code>.category.label` | Maps value code → display text |
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| `value` | Flattened array of measurements (row-major order) |
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### Row-Major Index Decoding
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Values are stored in row-major order: the last dimension (`month`) varies fastest.
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Given `size = [2, 72, 12, 10, 1, 1, 1, 2]`:
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- Flat index `0` → `[0,0,0,0,0,0,0,0]` = measure=MASS, species=TOTAL, ..., month=2024M01
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- Flat index `1` → `[0,0,0,0,0,0,0,1]` = measure=MASS, species=TOTAL, ..., month=2024M02
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- Flat index `2` → `[0,0,0,0,0,0,1,0]` = measure=MASS, species=SPECIES_1, ..., month=2024M01
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Decoding algorithm (reverse modulo):rust
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fn decode(flat_index: usize, sizes: &[usize]) -> Vec<usize> {
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let mut indices = Vec::new();
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let mut remaining = flat_index;
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for &size in sizes.iter().rev() {
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indices.push(remaining % size);
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remaining /= size;
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}
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indices.reverse();
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indices
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}
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### Sentinel Values
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| Value | Meaning |
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|-------|---------|
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| `-1.0` | Missing/no data (treated as `NULL`) |
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| `null` | Missing/no data (already nullable in JSON) |
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---
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## Known Constraints
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1. **Cell limit**: ~8 million cells per query
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2. **Rate limits**: Unknown — assume reasonable backoff for large downloads
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3. **Language**: API responds in requested language (`fo` or `en`)
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4. **Time zone**: No timezone specified — treat timestamps as local
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5. **Updates**: Data updated irregularly — metadata timestamp in response header
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---
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## Integration Checklist
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- [x] Metadata endpoint reachable via GET
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- [x] POST queries return valid JSON-stat2
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- [x] Dimension codes match `variables[].code` from metadata
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- [x] Row-major index decoding verified
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- [x] Sentinel value coercion (`-1.0` → `None`) implemented
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- [x] Unicode (Faroese characters) handled correctly
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- [ ] Incremental ingestion logic tested
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- [ ] Parquet export tested
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- [ ] Error handling for network timeouts implemented
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---
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## References
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- Official PxWeb documentation: https://pxweb.github.io/docs/
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- JSON-stat2 specification: http://json-stat.org/format/
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- Hagstova Føroya: https://www.hagstova.fo/
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