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Geocode Finnish Place Names or Street Addresses

Source: R/geocode.R
geocode.Rd

Geocodes Finnish place names or street addresses using the National Land Survey of Finland (NLS) geocoding REST API. This function converts textual location descriptions into spatial coordinates.

Usage

geocode(
  search_string,
  source = "interpolated-road-addresses",
  crs = 3067,
  lang = "fi",
  size = NULL,
  options = NULL,
  api_key = getOption("geofi_mml_api_key")
)

Arguments

search_string

Character. The place name or street address to geocode (e.g., "Suomenlinna" or "Mannerheimintie 100, Helsinki").

source

Character. The data source to search in. Must be one of: "interpolated-road-addresses" (default), "geographic-names", "addresses", "mapsheets-tm35", or "cadastral-units".

crs

Character. The coordinate reference system (CRS) for the output data, specified as an EPSG code. Must be one of "EPSG:3067" (ETRS-TM35FIN, default) or "EPSG:4326" (WGS84).

lang

Character. The language for the API response labels. Must be one of "fi" (Finnish, default), "sv" (Swedish), or "en" (English).

size

Numeric or NULL. The maximum number of results to return. Must be a positive integer. If NULL (default), the API’s default size is used.

options

Character or NULL. Additional options to pass to the API, specified as a single string (e.g., "focus.point.lat=60.1699&focus.point.lon=24.9384"). If NULL (default), no additional options are included. See the NLS geocoding API documentation for valid options.

api_key

Character. API key for authenticating with the NLS geocoding 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 geocoded locations as points in the specified crs. If no results are found, a warning is issued, and an empty sf object is returned.

Details

This function uses the NLS geocoding REST API to convert place names or street addresses into spatial coordinates. It supports multiple data sources, including interpolated road addresses, geographic names, and cadastral units. The function includes robust error handling:

  • Retries failed requests up to 3 times for transient network issues.

  • Handles HTTP errors and rate limits (HTTP 429).

  • Validates inputs to prevent common errors.

See also

geocode_reverse for reverse geocoding. https://www.maanmittauslaitos.fi/en/rajapinnat/api-avaimen-ohje for instructions on obtaining an API key. https://www.maanmittauslaitos.fi/kartat-ja-paikkatieto/aineistot-ja-rajapinnat/paikkatietojen-rajapintapalvelut/geokoodauspalvelu for more information on the NLS geocoding API.

Author

Markus Kainu markus.kainu@kapsi.fi

Examples

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

# Geocode a place name
locations <- geocode(search_string = "Suomenlinna", source = "geographic-names")
print(locations)

# Geocode a street address with a custom size and output CRS
addresses <- geocode(
  search_string = "Mannerheimintie 100, Helsinki",
  source = "addresses",
  crs = "EPSG:4326",
  size = 5
)
print(addresses)
} # }