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Query Geographic Names (Nimistö) from the National Land Survey of Finland

Source: R/ogc_api_nls.R
ogc_get_nimisto.Rd

Queries the Geographic Names (Nimistö) OGC API to retrieve spatial data on place names provided by the National Land Survey of Finland (NLS).

Usage

ogc_get_nimisto(
  search_string = NULL,
  collection = "placenames",
  crs = 3067,
  limit = NULL,
  bbox = NULL,
  custom_params = NULL,
  api_key = getOption("geofi_mml_api_key")
)

Arguments

search_string

Character or NULL. A search string to filter place names (e.g., "kainu"). The search is case-insensitive. If NULL (default), no search filter is applied, and all place names are retrieved (subject to the limit parameter).

collection

Character or NULL. The name of collection for places, place names and map names of the Geographic Names Register provided by the National Land Survey of Finland where the search if performed from. Supported values are placenames, mapnames, and placenames_simple

crs

Numeric or Character. The coordinate reference system (CRS) for the output data, specified as an EPSG code. Supported values are 3067 (ETRS-TM35FIN, default) and 4326 (WGS84). The returned sf object will be transformed to this CRS.

limit

Numeric. The maximum number of features to retrieve in a single API request. Defaults to 10. Set to NULL to fetch all available features (potentially using pagination for large datasets).

bbox

Character or NULL. A bounding box to filter the data, specified as a string in the format "minx,miny,maxx,maxy" (e.g., "24.5,60.1,25.5,60.5"). Coordinates must be in the same CRS as the API (EPSG:4326). If NULL (default), no spatial filter is applied.

custom_params

Character or NULL. Additional query parameters to append to the API URL, specified as a single string (e.g., "attribute='value'"). If NULL (default), no additional parameters are included.

api_key

Character. API key for authenticating with the Geographic Names OGC API. Defaults to the value stored in options(geofi_mml_api_key). You can obtain an API key from the National Land Survey of Finland website (see https://www.maanmittauslaitos.fi/en/rajapinnat/api-avaimen-ohje).

Value

An sf object containing the spatial features (place names) from the Geographic Names dataset, transformed to the requested crs. If no features are found, a warning is issued, and an empty sf object may be returned.

Details

This function retrieves spatial data on place names from the Geographic Names (Nimistö) OGC API, provided by the National Land Survey of Finland (NLS). It supports filtering by a search string (case-insensitive), spatial filtering using a bounding box, and limiting the number of returned features.

Key features:

  • Supports pagination for large datasets when limit=NULL.

  • Applies spatial filtering using a bounding box (bbox).

  • Transforms the output to the specified CRS (crs).

  • Validates inputs to prevent common errors.

See also

https://www.maanmittauslaitos.fi/nimiston-kyselypalvelu-ogc-api/tekninen-kuvaus for more information on the Geographic Names dataset. https://www.maanmittauslaitos.fi/en/rajapinnat/api-avaimen-ohje for instructions on obtaining an API key.

Author

Markus Kainu markus.kainu@kapsi.fi

Examples

if (FALSE) { # \dontrun{
# Set your API key
options(geofi_mml_api_key = "your_api_key_here")

# Search for place names containing "kainu" in EPSG:3067
places <- ogc_get_nimisto(search_string = "kainu")
print(places)

# Search with a bounding box (in EPSG:4326) and transform to EPSG:4326
places_bbox <- ogc_get_nimisto(
  search_string = "kainu",
  bbox = "24.5,60.1,25.5,60.5",
  crs = 4326
)
print(places_bbox)

# Fetch all place names (no search filter) with a custom limit
all_places <- ogc_get_nimisto(
  search_string = NULL,
  limit = 100
)
print(all_places)
} # }