Area code regions — bkg_area

Retrieves area code regions (Vorwahlgebiete) in Germany. Area code regions are based on the number of registered telephone numbers.

Usage

bkg_area_codes(
  ...,
  bbox = NULL,
  poly = NULL,
  predicate = "intersects",
  filter = NULL,
  epsg = 3035,
  max = NULL
)

Arguments

...

Used to construct CQL filters. Dot arguments accept an R-like syntax that is converted to CQL queries internally. These queries basically consist of a property name on the left, an aribtrary vector on the right, and an operator that links both sides. If multiple queries are provided, they will be chained with AND. The following operators and their respective equivalents in CQL and XML are supported:

R	CQL	XML
`==`	`=`	`PropertyIsEqualTo`
`!=`	`<>`	`PropertyIsNotEqualTo`
`<`	`<`	`PropertyIsLessThan`
`>`	`>`	`PropertyIsGreaterThan`
`>=`	`>=`	`PropertyIsGreaterThanOrEqualTo`
`<=`	`<=`	`PropertyIsLessThanOrEqualTo`
`%LIKE%`	`LIKE`	`PropertyIsLike`
`%ILIKE%`	`ILIKE`
`%in%`	`IN`	`PropertyIsEqualTo` and `Or`

To construct more complex queries, you can use the filter argument to pass CQL queries directly. Also note that you can switch between CQL and XML queries using options(ffm_query_language = "xml"). See also wfs_filter.

bbox

An sf geometry or a boundary box vector of the format c(xmin, ymin, xmax, ymax). Used as a geometric filter to include only those geometries that relate to bbox according to the predicate specified in predicate. If an sf geometry is provided, coordinates are automatically transformed to ESPG:25832 (the default CRS), otherwise they are expected to be in EPSG:25832.

poly

An sf geometry. Used as a geometric filter to include only those geometries that relate to poly according to the predicate specified in predicate. Coordinates are automatically transformed to ESPG:25832 (the default CRS).

predicate

A spatial predicate that is used to relate the output geometries with the object specified in bbox or poly. For example, if predicate = "within", and bbox is specified, returns only those geometries that lie within bbox. Can be one of "equals", "disjoint", "intersects", "touches", "crosses", "within", "contains", "overlaps", "relate", "dwithin", or "beyond". Defaults to "intersects".

filter

A character string containing a valid CQL or XML filter. This string is appended to the query constructed through .... Use this argument to construct more complex filters. Defaults to NULL.

epsg

An EPSG code specifying a coordinate reference system of the output. If you're unsure what this means, try running sf::st_crs(...)$epsg on a spatial object that you are working with. Defaults to 3035.

max

Maximum number of results to return.

Value

An sf dataframe containing polygon geometries and the area code (vorwahl) associated with the region.

Query language

While other WFS interfaces like bkg_admin allow querying using CQL or XML, bkg_area_codes ONLY supports XML. This has implications for the allowed query filters (see wfs_filter).

Examples

vorwahlen <- bkg_area_codes(vorwahl %LIKE% "0215%")
plot(vorwahlen$geometry)