Add a feature to an Overpass query

Add a feature to an Overpass query

Usage

add_osm_feature(
  opq,
  key,
  value,
  key_exact = TRUE,
  value_exact = TRUE,
  match_case = TRUE,
  bbox = NULL
)

Arguments

opq

An overpass_query object

key

feature key; can be negated with an initial exclamation mark, key = "!this", and can also be a vector if value is missing.

value

value for feature key; can be negated with an initial exclamation mark, value = "!this", and can also be a vector, value = c ("this", "that").

key_exact

If FALSE, key is not interpreted exactly; see https://wiki.openstreetmap.org/wiki/Overpass_API

value_exact

If FALSE, value is not interpreted exactly

match_case

If FALSE, matching for both key and value is not sensitive to case

bbox

optional bounding box for the feature query; must be set if no opq query bbox has been set

Value

opq object

Note

key_exact should generally be TRUE, because OSM uses a reasonably well defined set of possible keys, as returned by available_features. Setting key_exact = FALSE allows matching of regular expressions on OSM keys, as described in Section 6.1.5 of https://wiki.openstreetmap.org/wiki/Overpass_API/Overpass_QL. The actual query submitted to the overpass API can be obtained from opq_string.

add_osm_feature vs add_osm_features

Features defined within an add_osm_features call are combined with a logical OR.

Chained calls to either add_osm_feature or add_osm_features() combines features from these calls in a logical AND; this is analagous to chaining dplyr::filter() on a data frame.

add_osm_features() with only one feature is logically equivalent to add_osm_feature().

References

https://wiki.openstreetmap.org/wiki/Map_Features

See also

add_osm_features

Other queries: add_osm_features(), bbox_to_string(), getbb(), opq(), opq_around(), opq_csv(), opq_enclosing(), opq_osm_id(), opq_string(), overpass_status()

Examples

if (FALSE) { # \dontrun{
q <- opq ("portsmouth usa") |>
    add_osm_feature (
        key = "amenity",
        value = "restaurant"
    ) |>
    add_osm_feature (key = "amenity", value = "pub")
osmdata_sf (q) # all objects that are restaurants AND pubs (there are none!)
q1 <- opq ("portsmouth usa") |>
    add_osm_feature (
        key = "amenity",
        value = "restaurant"
    )
q2 <- opq ("portsmouth usa") |>
    add_osm_feature (key = "amenity", value = "pub")
c (osmdata_sf (q1), osmdata_sf (q2)) # all restaurants OR pubs

# Use of negation to extract all non-primary highways
q <- opq ("portsmouth uk") |>
    add_osm_feature (key = "highway", value = "!primary")

# key negation without warnings
q3 <- opq ("Vinçà", osm_type = "node") |>
    add_osm_feature (key = c ("name", "!name:ca"))
cat (opq_string (q3))
q4 <- opq ("el Carxe", osm_type = "node") |>
    add_osm_feature (key = "natural", value = "peak") |>
    add_osm_feature (key = "!ele")
cat (opq_string (q4))

# Get objects with keys (`natural` OR `waterway`) AND `name`
q_keys <- opq ("Badia del Vallès", osm_types = "nwr", out = "tags") |>
    add_osm_features (features = list (natural = NULL, waterway = NULL)) |>
    add_osm_feature (key = "name")
cat (opq_string (q_keys))
} # }